I don’t need to tell any of you that home runs are up, right? That’s an analytical conversation that has long since permeated the average baseball-ing household. There are more frequent home runs than there used to be. There were signs of a weird spike beginning around the 2015 All-Star break. It’s not because of the ball! At least, there’s no convincing evidence pointing to it being because of the ball. Home runs are just up, and it’s a thing we’ve gotten used to.
There was a time that identifying the home-run spike might’ve counted as groundbreaking. That time has passed. All I’m here to tell you today is that the home-run spike is still spiking. Rates, I mean, haven’t plateaued. They’re still going up. Home runs continue to take offense by storm. Here are home-run rates going back to 1954, with all plate appearances as the denominator:
This current June is the 379th month in the sample. And although this current June still has a long ways to go, it has what would be the highest home-run rate for a month. May would rank third-highest. So, that’s something. But then, there’s also the matter of this — contact has been going down. Here are the monthly rates of plate appearances ending with a batted ball hit fair:
Nothing you didn’t know about in there, either. But now let’s combine the two, looking at home-run rates, with batted balls as the denominator instead of plate appearances:
Just so you know, I went back to 1954 because that’s the first year of Baseball Reference having record of sacrifice flies. Nothing that happened before 1954 would change the overall picture. In terms of home runs on contact, this June would easily rank first. May is in second. April is in seventh, even though April historically has the lowest home-run rates for any month out of the six. Baseball is on its 15th consecutive regular-season month with a higher home-run rate on contact than the previous season’s equivalent month. Homers this April were up 12% over last April, which were up 18% over the previous April. Homers this May were up 12% over last May. Homers so far in June are up 10% over last June. Where we are now, 5.12% of fair batted balls in June have been homers. It’s the first time baseball’s broken the 5% threshold.
April had the second-highest homer rate for any April, narrowly behind April 2000. May had the highest homer rate for any May. June has what would be, very easily, the highest homer rate for any June. It’s enough to make you wonder about July, August, and September. I don’t know where the trend is going to go, but I could offer a guess, based on the fact that absolutely nothing here has slowed down.
The home-run era is welcoming even more home runs. Many people have their guesses for why this is taking place. Nothing, as far as I know, has been proven, conclusively. All that’s truly been proven is that home runs are everywhere. I’d tell you to get used to it, but then, you probably already have.
Jeff made Lookout Landing a thing, but he does not still write there about the Mariners. He does write here, sometimes about the Mariners, but usually not.
Do we need to consider that new harder to detect drugs are out there? Testing got better but with new substances, masking agents, micro dosing and cycling it only in the off-season there are probably ways to beat the tests.
I don’t want to accuse singular players but the average player is now even bigger and stronger than in the so called steroid era.
In lance Armstrong’s day there also was a lot of testing and not many were caught.
Sure awareness of launch angle, better training and nutrition sure plays a role but the way there are not only more HR but also pitchers throwing harder every year I think we need to consider at least the possibility of a PED problem.
There is just too much money in it to not at least consider it.
Im sure there are a lot of clean players too but I would not rule out that it would be like in cycling in the mid 00s either.
Haven’t we kind of discovered that PEDs probably weren’t actually that performance enhancing, anyways? 
No, they definitely enhance performance.
People are going to be upset by this comment, but it’s almost definitely the truth.
All pro sports are riddled with PED use. When money is involved, PEDs get used. They are hard to detect, and easy to use. The testing is way behind.
First, declaring something a PED doesn’t make it so. Many things on banned lists have been studied extensively and to date no detectable effect has been found. HGH is the highest profile among these, studies of exogenous HGH in young adults with normal HGH levels have found it to be a performance inhibitor as it reduces stamina. Essentially, your body already makes as much HGH as it can effectively use…taking more doesn’t help. Also, almost everything you can get at GNC is useless and the things that aren’t are mostly amphetamines.
Second, just because anabolic steroids can make you stronger does not mean that it will have a big effect on highly derived skills such as hitting a baseball. The strongest guys in MLB are not the guys that hit the most HRs…though a lot of the tallest guys are because if those guys get proper rotation the axis around which their bat moves is huge, leading to incredible bat speed.
Finally, the timeline of changes in power production in MLB simply do not match up at all with what is known or what is suspected of the history of PED use in baseball. There are huge discontinuities that can’t be accounted for unless you think everyone started using at the same time, then stopped taking at the same time, then started taking at the same time…and somehow that none of the 100s of players doing it talked (or that any of the pitchers would out them).
So what made mcgwire and sosa double their hr from 35 to 70 HRs?
There is a clear relationship between strength and power, many sprinters have used steroids with big success.
It doesn’t make a hitter that cant hit good but it can increase batspeed, quickness and power.
Im not saying that there is a problem with steroids but I think it needs to be considered a possibility.
I dont think PEDs are the main reason for the 2015 spike though, it just happened to quickly to be caused by that.
I’ll give you that Sosa nearly doubled his total, but McGwire was a bona fide threat to Maris’s record the day he set foot in the majors.
1993-1997 versus 1998-2001 Sosa’s HR rate increased by 59%. So PEDs.
Those were Sosa’s age 24-28 versus 29-32 seasons. In the last 30 years, 29-32 year olds had a 4.7% higher home run rate than 24-28 year olds.
MLB as a whole, 1993-1997 versus 1998-2001 went up 10.8% as far as home run rate.
So, while that 59% jump is huge a player Sosa’s age those years was perhaps expected to jump about 16%. So, a decent chunk of his increased power is explained right there.
McGwire hit 49 HRs his rookie year. Maybe he doesn’t hit 70 in 98, but I believe he would have hit around 60 “clean”
I think you’d have to be naive to believe that nobody’s on PEDs but the way the rise in home-runs arrived so suddenly and uniformly makes me doubt it can be attributed to PEDs. If that was the case, why would we only start seeing a spike in homers in the middle of the 2015 season? Why are most of the gains being seen in players who were at the lower end of the bell curve instead of everybody hitting a few more? I don’t think it makes a lot of sense.
Now, if you want to start talking about juiced ball conspiracy theories, I’ll happily put on a tinfoil hat and start going full Alex Jones. Imo, it’s the explanation that makes the most sense and I still haven’t seen an article that’s made me think otherwise.
I’ve read a bunch of articles on juiced balls, but I haven’t read any about bats. I’ve read the bat makers are getting better about selecting and shaping wood and that some hitters are using different bats, but nothing on the impact of these mostly incremental changes on home runs. Anyone have a good read to recommend?
I’m also a happy juiced ball conspiracist. But doesn’t the fact that the HR rate is continuing to slowly rise argue against that theory? Is MLB continuing to release juicier and juicier balls in an effort to conceal their plot? I frankly don’t give them credit for being that clever.
There is also the chance that the ball is juiced and now players who previously had warning track power can hit it out and thus try to elevate more. The more flies go out the higher the inventive to lift it in the air.
My theory is the juiced ball could’ve led to an immediate spike in homers and then the continued rise is the result of the league adapting and emphasizing launch angles, but yeah, that’s a good point. If the rate doesn’t start to stabilize out within another year or so it’s a pretty big argument against the juiced ball theory so I guess we’ll just have to wait and see.
“Juicier and juicier balls!” Oh my.
I’m totally onboard with the juiced ball theory. This THT article suggests atmospheric effects isn’t the issue, and neither are launch angles.
On the first point: the change from 2015 to 2016 that any ball in the angle/EV sweet spot will go over the fence … is zero. On the second point: the number of home runs at a good launch angle increased far more than the number of balls hit at that angle.
So it has to be exit velocity. What could cause that in the middle of a season? Very unlikely that everyone changed their swing approach, or that lineups changed dramatically to introduce more hard swingers, or that a ton of players were convinced to use PEDs while watching the All Star Game. It’s just far more likely there was an equipment change (i.e. a new ball).
The author of that piece points out that low angles didn’t see much change in EV, and with a juiced ball you ought to expect those to change as much as the other angles. But it’s not that weird if you think of ball juicing not as a matter of the internal behavior of a ball (springier or whatever), but rather about how the surface of the ball interacts with the bat. Liners are hit so straight that a smooth ball surface is basically the same as a rough ball surface. But with a bit more loft, the interaction of the two surfaces may be significant. I don’t know whether you want a “grippier” leather (sends the ball toward the fence faster on balls you get under slightly) or a “slicker” leather (gives it more backspin on balls you get under slightly), but my money is on a change to the surface.
File that under “no convincing evidence”… right next to Nate Silver’s work. It is telling that the Fangraphs authors are against the juiced ball theory despite the reasonable arguments for it. Everyone wants to believe that Statcast is at the heart of a revolution – it is certainly a narrative that gets told often and it is an easy sell. When an entire community has a pro this or that agenda, you have to question the message… well, I do at least.
The spike in the spike makes sense if balls are juiced. It would have taken the players a while to realize that they could get away with things (like hitting as many flyballs as possible) that did not work at any other level. Once the game changes, the players follow – just like they did the last time things changed around the turn of the century… no, this time its data!
There it is! The person claiming that the alternate theory is a conspiracy theory. Great point!