Diving Into First Base: Maybe Not Crazy
“Chester wouldn’t play baseball unless Wilson played, and they never swung at the first pitch or slid headfirst.” — Chester’s Way, by Kevin Henkes
Most of us have been taught that running through the bag is unequivocally faster than diving into it. Those who dive into first base are often ridiculed for doing so, risking injury to themselves while simultaneously making themselves less likely to beat the throw. However, a new way of thinking about the physical effects on the runner as he dives through the bag — pioneered by the father/son duo that make up “Baseball con Ciencia” — shows that the diving runner could close the distance to the first base bag at a faster rate. Theoretically.
Let’s put aside the risk of injury for now. Diving into the first base bag puts appendages at risk that would not having anything to do with running through that same bag. But that’s another topic. For now, we’re just concerned with the physics of it all.
For now, let’s just talk about the dive into the bag in three parts, as Norberto Rivas Sr and Jr have done on their blog.
The Preparation for the Jump
In order to jump down towards the bag, the runner has to get more horizontal. That’s just how it works. Getting horizontal may not seem to be an advantageous thing in itself, but getting there does two things that help. In going towards the earth, your body is allowing gravity to help it lean forward. This stretches out your stride, as well. Here’s what it looks like on a collection of stills from Baseball con Ciencia:
By the calculations of the Rivas duo, this step gives the diver a ten centimeter advantage over the runner. Not large, but it adds up.
The Jump
There are two advantages to jumping.
The first is mechanical or muscular. After preparing to jump, your body is pointed in one direction and the lunge can be one last explosive movement from your legs. In other words, while you are running upright, you’re using your muscles to push both horizontally and vertically. In the dive, you’re doing a squat, and pushing entirely in one direction.
It’s certainly possible that, in some sports, your vertical muscles would be less developed than your horizontal ones. Long distance running, perhaps. But short distance runners and baseball players usually develop both aspects of their muscles, as recent running theory has shown is a smart idea. So if you do squats, that dive can be powerful, as it fully uses one of the largest muscles in your body to push in one direction. You can read a little more about this phenomenon in this excellent post by David Kagan on The Hardball Times.
The second advantage to jumping comes from the fact of flight. You’re no longer connected to the ground, and you are allowing gravity to fuel your flight as you fall closer to the base.
There is some deceleration due to air friction — Physics professor Alan Nathan called air friction’s impact minimal in this situation — but then there’s actually acceleration on the second half of the fall according to Rivas. Rivas explained in an email. “We found a deceleration, as expected, from 9 m/s to 8.35 m/s on the first 1.08 meters of hip flight,” he admitted. “But on the second 1,05 m. of flight, we register an acceleration, passing from 8.35 m/s to 8.68 m/s. This acceleration was limited, because, as soon the hands’ friction with the floor occurs, the deceleration by body/floor friction begins.”
The Rivases estimate that the explosion plus the flight increases the divers’ advantage over the runners by .71m, and made a video showing the difference in controlled conditions — one runner, synched to himself to show the advantage.
They key to maintaining the advantage is technique. According to Rivas, “The average velocity reached by the runner in the last long step is 9.5 m/s. The average velocity of first .6 meter of sliding is 6.2 m/s, and the average velocity of full body sliding was 5.2 m/s.” Since the diver had a .81m headstart at the end of his dive (25.6 inches), it should take much more than a meter (three feet) of sliding for the runner to overtake the diver.
Nathan, when contacted, felt it is possible that, under the right conditions, the diver could beat the runner. He wasn’t sure about Rivas’ explanations, though. “It could be simpler — you’re stretching your hand out, and the extremity of your body is touching the bag before the rest of your body.”
The roles of gravity and air friction might be overrated in this analysis, he felt, but he did admit that gravity would give your body an assist by “helping to provide the torque” necessary in getting into a diving position. That links up at least generally with what the Rivases say about the benefits of the diving position above. If your technique is right, gravity helps your body along.
But really, the whole advantage gained throughout the dive depends on technique, according to the Rivas family. Their main critiques of the ESPN Sports Science takedown of diving had to do with two points.
One, they felt that Sports Science didn’t make sure that the two runners being compared were at the same velocity going into the slide, which might be a matter of science or technique.
Two, they felt that the example runner did not make enough of the muscular advantage gained by lunging. You’ll see Barry Larkin and Harold Reynolds discuss some of the proper technique of running into a dive into first here. They even mention the aspect of keeping the sliding distance short. Rivas feels that the proper technique has a runner beginning the process at 23 feet, diving at 13 feet, and sliding about a foot or less to the bag.
And, let’s return to the injury factor that we left alone at the beginning of this piece. Even if Nathan believed it was possible for the diver to beat the runner, he thought it was a dangerous activity, particularly since he felt the runner should literally be diving straight for the bag.
Rivas once again felt that technique was the answer here, too. He pointed out that Brett Gardner does a great job of sliding on his wrists, not his palms, so that he can keep his fingers up, and included a still of Gardner sliding as a reference point.
In the opinion of Rivas, the action is low risk with the right approach. But it does seem like a lot of this hangs on technique. You certainly wouldn’t want your Josh Hamiltons sliding into first base regularly; that’s an easy way to get hurt.
But your Brett Gardners? They are used to sliding head first, and they know how to use their last explosive movement going into the slide correctly. They might actually get an advantage from diving into that first base bag. At the very least, it might not slow them down enough to be worth all the outrage.
With a phone full of pictures of pitchers' fingers, strange beers, and his two toddler sons, Eno Sarris can be found at the ballpark or a brewery most days. Read him here, writing about the A's or Giants at The Athletic, or about beer at October. Follow him on Twitter @enosarris if you can handle the sandwiches and inanity.
Again, why do people refuse to believe this? You don’t see outfielders trying to run out every ball; they dive when it’s too far away to reach. It’s nice to see the physics and whatnot behind this, though.
Outfielders dive because you cannot catch a ball with your feet.
The case for diving into first would be ironclad if you had to touch the base with your hand.
I replied without even seeing yours first… I wasn’t copying you, I swear! 😀
Yes, I know that, and I should have mentioned something about it. Even if they were only trying to kick it there is just no way to reach a bunch of those balls. There aren’t a lot of chances for shoestring catches.
Diving in the field also gives you the extra time it takes for the ball to travel from your upper body to the level you reach in your dive. Not the case for first base.
If your suggestion is correct, wouldn’t we expect soccer players to never making diving header plays? I mean, they CAN make the play with their feet. Why not do so?
I imagine it is because they can get their head to the ball with a diving motion faster than they can get their feet there by running. I suspect THAT is the same general principle behind outfielders diving.
What? No, soccer plays CAN’T make all plays with their feet. If the ball is travelling in front of the player, perpendicular to the players path at a good clip, at say 6 feet high, a header is pretty much the only way to make contact with the ball.
Your analogy doesnt really work.
cs3,
I don’t know why the website won’t let me reply specifically to your comment. Best attempt I can make here.
Nothing in what I wrote suggested that soccer players will be capable of making EVERY play with their feet. Further, what I wrote ought to have suggested that I was referring to plays where the ball is significantly nearer to the ground than what you have described (6ft off the ground); that is why I posted in response to a discussion of diving catches in the outfield – a scenario in which the ball is near to the ground. I thought it would’ve been clear that I was discussing cases where the ball is low, not up at 6 ft, which would obviously be disanalogous to a diving catch in the outfield.
Maybe this Ronaldo clip – https://www.youtube.com/watch?v=06vWyHbeu3A – gets closer to what I mean. Sure, he isn’t on the ground, but I think it is clear that he heads the ball well lower than 6ft, and I would argue the ball was low enough that he could’ve made a play with his legs (or at the very least his torso). Why didn’t he do so? I *suspect* it is because diving for a header was actually faster than the alternative.
Or how about this clip? https://www.youtube.com/watch?v=Ev1S8quL9rE The dude pretty clearly misses, but the intent is there. Why not just lunge at the ball with his feet? Wouldn’t that be faster, under Sweeney’s thinking?
Because just touching the ball with your foot doesn’t qualify as an out, but touching the base with your foot (could) qualify as being safe.
If you could catch with your foot then outfielders wouldn’t have to dive to catch a ball. The fact that you can touch the bag with your foot which is naturally closer to the ground gives you another advantage. When running to the base, your hand will need to travel a further distance than your foot to reach the base. It might be that under perfect conditions you can make it to the base the slightest fraction of a second faster but in reality, over 90% of the time, you will slide sub-optimally and make it take longer.
You can find dozens of studies showing that it takes longer to slide than to run through the base and just because one person publishes a something showing a different result doesn’t invalidate all the other studies on the subject. I appreciate that Eno is looking at a different approach since I feel like he explores the other side of what is widely accepted better than most do, I just don’t think that this invalidates years of research.
Actually, I’ve always agreed with this point, too. I think it is too difficult to be consistently perfect for diving to actually be worth it. It’s one of those things that I’d pull out in a desperate situation where I knew I’d be out but maybe a lucky perfect dive gets that extra tenth of a second.
I’m not actually advocating that it be done often, just that it IS viable (potentially).
Except if it’s something you only pull out in desperate situations, you have even less practice at it and are less likely to do it well.
Thanks Eno, very interesting article.
Two thoughts I have on the dive into first:
1. If diving could accelerate the time for a runner to hit the target, how come we’ve never seen an Olympic sprinter dive right before the finish line?
2. Has anyone ever broken down the % of dives into first that came because of a potential tag play from the first baseman (because of an errant throw)? This is the one play where the headfirst dive is truly called for.
because it might hurt more?
because a track has more friction?
And, upon further review of the comments from Michael Sweeney and KSU, I think I made a totally bad analogy. In track you don’t have to touch anything, other than your body breaking the plane of the finish line. Sprinters can best do this by leaning their bodies forward at the last second to break the plane.
So, the answer to my first question is, nevermind.
not quite equivalent
baserunning, you have to hit a point on the ground
fielding, you have to hit a specific, moving point somewhere in the air
in track, you just have to cross the plane, at any height
Theoretically, you could still make an argument that diving through the finish line would be superior than leaning forward (outside of track surface)
I tried to answer it anyway. Below.
Gold metals cure all pain
1. They actually do dive, all the time. Go watch some olympic trials and let us know about diving in races :p
tz, actually you’ve unintentionally stumbled on (pun not intended) part of the answer.
The batter/runner’s stride is a factor in this. Part of the optimal way to run through first base is having your left foot strike the bag half on, half off. In other words, toes strike bag, heel not on bag. Running to first at anything less than 100% (a lot of players) even 99% and any pro baseball player can pretty much synch up their front left foot to strike the front of the base that way. Going at 100% and your strides lengthen there’s some variation and it’s not quite clear where your foot will strike. Remember you only see slides into first on the very closest plays, and not on the “beat em by a step” plays which aren’t as close. So there are a handful of guys who would rather dive head first than worry about altering their stride to strike the bag optimally, which would slow them down. So that’s part of it. End of riff.
Sprinters have to get their torso across the line first to win; batters have to get one extremity to first base to be safe.
The difference doesn’t prove anything but does allow the possibility that the fastest strategy in once sport might not be the fastest strategy in a different sport.
Also, it is possible that by looking at elite athletes from different sports, you are already selecting for different skill sets. Baseball players are more likely to be capable divers (in relation to their running skill) than a runner who is selected entirely because of his/her ability to run in an upright position.
looks like the potential for a lot of broken fingers, hands, and arms to me
Diving into first only makes sense, to me, if there is an errant throw that will possibly draw the 1B off the bag and make it a tag play.
If only there were some analysis of the situation you could read to make an informed decision!
I think the only way to settle this is for Carson Cistulli to perform a video demonstration of both techniques #keepnotgraphs
I would say replace Carson with Banknotes Harper, but his engorged member hitting the ground at his maximal running velocity would likely trigger a massive fissure of the earth’s tectonic plates, as well as spontaneous orgasms of every notary public in the world.
It seems risk-reward to me, one extra single doesn’t outweigh the large risk of injury. When you dive at first there is always a foot wearing spikes involved that’s aiming for the same approximate area, and most likely the pitcher, the least athletic member of the infield.
I don’t advocate for diving into first, but I do hate it when people declare something an absolute. Maybe there is a slight advantage to diving if you do it correctly. These guys are professional athletes that have been playing this game their whole lives, if somebody like Brett Garner thinks he can gain an advantage of being safe and the reward outweighs the risk, then let him do it.
I do recall last year the Nationals saying their research shows sliding headfirst is no more dangerous than sliding foot first (not that you would slide foot first, but this was in reference to people saying Harper should cool it with the head first slides), so my point is, if you’re an expert base runner and are comfortable diving, it shouldn’t be too dangerous.
Now having some lumbering first baseman/DH that doesn’t run the bases that well? Yea, avoid diving at all costs.
Why won’t my comment post?
Well well, that one certainly did. Disregard.
are you a robot? Robots can’t post anymore
Here I am, brain the size of a planet, and they tell me that I can’t post on Fangraphs anymore. You call that fair? ‘Cause I don’t.
So diving is faster if all the conditions for diving (distance from bag, the runner’s speed, the runner’s technique) are ALL perfect. If any of those factors are off even a little, then the dive won’t work. And considering that the risk of injury is greater than if the runner had simply run through first base, it seems the risk of diving far outweighs any potential reward.
We should not forget the umpires in all these discussions. It is much harder to judge a sliding runner than it is to judge one who is running through (unusual movement, much more dust/dirt that obstruct the view less accustic signals) and I think that they are more likely to call an out on a close play.
Maybe it is possible to look at some data of very close plays at first and check how the percentages of the calls went when runners slid / ran through.
Results may vary for umpires though as I’m sure some favor and reward sliding runners and others penalize that technique. There is propably not enough data available though.
Replay is a thing now.
In what direction is the acceleration measured for the second half of the fall? Pointing directly to the bag?
If you leave your feet traveling at 9 m/s, and decelerate to 8.35 m/s, there’s NO WAY you could accelerate in mid-air back up to 8.68 m/s if all we’re talking about is in the x-direction (horizontal). The only acceleration you could possibly experience once you’re mid-air is due to gravity, which would all be in the y-direction (vertical)
It’s a small point, and probably irrelevant, but can you really accelerate in the horizontal mid-dive? I don’t know any better but that doesn’t sounds right.
Yea Brett I thought the exact same thing. The only way I could think to make it work as the article suggests is that they’re measuring acceleration on the vector pointed directly at the bag from like the runner’s chest I guess? Which would be like a 30-degree downward plane, and I suppose as you fall the acceleration due to gravity along the y-axis could contribute enough to your acceleration along that diagonal vector to make it increase ever so slightly.
Sure. Just turn your jet pack on.
It does accelerate. Saying it’s due to gravity is partially correct. What I think they’re measuring is the horizontal position of the front most part of the body. Going into the slide, this is the hands. The hands extend from the arm muscles which contributes to acceleration, but they also accelerate due to the lengthening and laying out of the body. The torque required to turn the body vertical to horizontal is decreased due to gravity. So gravity helps you turn, and other muscles besides your leg muscles, core and arms(for extension) also help you turn. Thus, in diving, you get forces applied from not just your leg muscles, but also core and arm muscles as well as gravity to help you reach optimal position. This results in acceleration.
Taking away the risk factor which should stop the discussion immediately, the idea that you gain speed/distance by getting into the lunge/predive position makes little sense. The diving runner would decelerate as their body shifts position to dive versus the runner who should be hitting peak speed as they reach the bag.
There’s also a slim chance of an errant throw to first, and if you dive, you’re basically cutting down those chances of getting an extra base in many of those instances. Obviously not a large difference, but if we’re talking fractions of a second here…
Take a few people who make a habit out of diving to 1st.
For each calculate the speed for times when they dove vs when they were hustling through the bag to beat a close throw.
Make comparisons for each runners diving speed taking into account age, injuries etc.
Also: steps are quantized; a slide is continuous. there may be cases where someone is sliding and has a center of mass behind a runner still on his feet but is still able to make contact with first base earlier.
And when players try to make that last stretch to beat out the throw running, there is injury potential there, too.
How many hyper-extended knees or pulled hamstrings or dislocated ankles are caused by making that last stretch with a foot instead of a hand?
I don’t doubt there is a somewhat higher risk by diving, but I think it’s overblown a bit without taking into account the overall injury risk that every batter takes.
I think it was during the world series game 7 review of Panik/Crawford double play that one of the announcers (probably on KNBR) said that the umpire would listen for the bang/bang of the ball in glove/foot on bag to make a lot of determinations.
Sliding head first removes the foot on bag thump, which, in the days before replay, might have led to increased safe calls due to uncertainty on the umpire’s part. I wouldn’t be surprised if reply sees the number of head first slides into first decrease.
There’s also a statcast of that double play, which discusses the timing of Hosmer’s slide: http://m.giants.mlb.com/news/article/100050584/joe-panik-doesnt-panic-on-crucial-giants-double-play
Umpires watch the runner make contact with the bag, and listen only for the sound of the ball hitting glove, not both sounds.
Your body is remarkably good at figuring out the most efficient way of performing physical tasks. The fact that many people instinctively dive into first base suggests to me that it could be faster, under the right conditions. I’m still not completely convinced, and I am sure that it is not correct to dive on every close play at first. But I do agree that this should not be dismissed out of hand. Is there any concrete evidence of increased risk of injury while diving into first base? Running full speed to the same spot another 200 lbs athlete is also running towards isn’t exactly safe to begin with.
Kids or young adults reading: Any reward for diving into first base is usually negated by the possible risk. Broken toes, hands, fingers, wrists, arms, you don’t want these young in life or at any time in life.
For the adults reading: Good article. Thing is, it seems like the only time a time should even think about recommending doing it would be if the big game is on the line for the season or what not. Any other time, even if you gain a half of second (debatable) just doesn’t seem worth any rewards it might bring.
Brett Gardner reduces the chance for injury to his fingers by sliding on his wrists instead of palms. However, he also reduces his extension by several inches by keeping his fingers up. Feels like some M. C. Escher logic going on here.
Gravity is not helping a player move closer to the bag horizontally (along the X-axis) at all. It only affects acceleration along the Y-axis. So, yes, it might help a player fall towards the ground, but that in no way makes sliding/diving faster than just running through the bag – the players feet are already on the ground, so gravity is only helping the players hands get to where his feet already are.