About All These Velocity Spikes

Yesterday, I wrote about Madison Bumgarner looking like he might have been throwing harder than usual on Sunday. Then Jeff chimed in, noting that most everyone in that game had increased velocity, and so perhaps there was something going on with Arizona’s radar calibration. In the comments of those pieces, several people noted that the ESPN broadcasters had mentioned that MLB was changing the way velocity was tracked this year, and thus we should expect higher readings in general this year than we’ve seen in the past.

Now that we’ve had the second “Opening Day” of the season, we now have data from 14 parks instead of just three, which gives us a chance to look at whether Arizona was an abnormality on Sunday, and whether the broadcasters were correct that we’re going to be seeing higher velocity numbers this year than in the past. And while we’re still dealing with small samples, if there was a systematic measurement change, it should show up pretty quickly. So let’s take a look at some numbers.

Last April, the average fastball was thrown 92.2 mph, based on the data we pulled from MLB’s PITCHF/x files. Through the first 14 games of this season, the average fastball was thrown 93.3 mph. And it’s not just fastballs. Curves have gone from 77 to 78 mph, sliders from 84 to 85 mph, and cutters from 88 to 89 mph. Looking at April to April velocity, everything is up about one tick from the same month a year ago.

To eliminate the chance of this just being the result of a new wave of hard-throwing pitchers who happened to pitch in their team’s first game of the season, but didn’t pitch last April, I pulled the data for every pitcher who has already pitched this year and threw a pitch in the first month of the 2016 season. 97 different pitchers have already recorded data in both April of 2016 and 2017, and the collective average fastball for these pitchers has gone from 92.3 last year to 93.2 this year, basically matching the league-wide change.

And it’s not just a few guys with huge moves at the top pulling up the average. 47 of those 97 pitchers had a first game fastball tracked at least one mph faster than their April fastballs were a year ago, and 70 of the 97 were up at least 0.1 mph. Only eight pitchers were down at least one mph from where they were last April, while 20 guys were up at least two mph.

I should note that Bumgarner is 11th on the list of bumps up from last year, and the top few guys (Raisel Iglesias and Jorge de la Rosa) are relievers who were starters a year ago, so among guys pitching in the same role, Bumgarner has had one of the largest measured changes in velocity so far. But it seems pretty clear that this isn’t just a bunch of guys throwing weighted balls over the winter and coming into camp throwing harder now; the data supports the idea that the velocity readings we’re getting this year are just going to be faster than the ones we’ve gotten previously.

In our live blog yesterday, a reader noted that the Brewers broadcasters made a similar comment to the ESPN broadcast on Sunday, suggesting that MLB was changing the point at which velocity was measured this year, so viewers should expect higher velocity numbers due to that change. Since two different TV broadcasts made the same comment, it seems pretty clear that this was something they were told in preparation for the season, so I asked Mike Petriello of the MLB Statcast team for some clarification.

Mike noted that MLB hasn’t actually changed the point at which they’re measuring velocity, but that this year, the conversion from PITCHF/x to Statcast has been completed, and all the tracking data in Major League stadiums is now coming from the Statcast system. For the last two years, PITCHF/x cameras continued to capture data as they had previously, and since sites like ours and BrooksBaseball had been setup to collect data from the MLB logs during the PITCHF/x era, our sites continued to pull PFX data up through last year.

This year, however, with Statcast officially replacing PITCHF/x in the big leagues, the data being pulled publicly is now from the Trackman radar. While PITCHF/x velocity numbers were reported at a defined point along each pitch’s trajectory — usually at the 55 foot mark — so that velocity didn’t have to be calculated at every x/y point along the pitches path, Statcast outputs the highest velocity that Trackman records along the flight of the pitch, which due to physics, is going to be immediately after the ball leaves the pitcher’s hand.

So what the broadcasters have said is true; MLB is essentially measuring velocity out of the hand this year, while the publicly collected data from prior years was measuring velocity at a point a few feet closer to the plate, so the readings showing up on TV and on FanGraphs in 2017 will be higher than they were in the past. But this wasn’t MLB moving the point at which they were measuring velocity; this was just the result of switching from PITCHF/x to Trackman, and the different outputs from a camera-based system to a radar-based system. If you compare Statcast velocity from last year to Statcast velocity from this year, you can get around this systematic shift, and more easily compare apples to apples.

But since we don’t have Statcast velocity for as many years as we have PITCHF/x velocity, it’s still useful to know how to compare them on the same scale, and it looks like the adjustment is on the order of about one mph. So if a pitcher’s recorded velocity is one tick faster this year than it was a year ago, he’s probably the same. And the magnitude of the change for a guy like Bumgarner, who was up 2.5 to 3.0 mph on all his pitches in his first start, is less extreme than it might seem on the surface, though it still seems likely he was throwing harder on Sunday than he was a year ago.

The other side of this coin is that guys who are just down a little bit this year are probably more worrisome than the raw numbers make it look. Sam Dyson, for instance, had a recorded fastball of 93.9 mph in his appearance yesterday, which isn’t that far off the 95.2 that we had for him a year ago. Except 93.9 in Statcast velocity is more like 92.9 in PITCHF/x velocity, which is where the 95.2 came from. And indeed, Baseball Savant — which only uses Statcast data — has Dyson down over two ticks from where they had him last year. So, yeah, it’s just one outing in early April, but Dyson is a guy to keep an eye on, given that he was throwing diminished stuff and got rocked yesterday.

The overall story, though, is that you should indeed expect to see higher velocity numbers from Statcast this year than you’ve expected from PITCHF/x over the last decade, on the magnitude of about one mph. If a guy is up in that range from a year ago, it’s the same stuff. If he’s up a few ticks, he’s probably up one tick. And if he’s down relative to last year, well, then you hope it’s just early and he gets his stuff back, and that you hope your team didn’t recently give him a $206 million contract for his decline years.