Changing Fastballs, by Movement

There’s something about the calendar flipping from April to May that makes it seem like the baseball season is somehow better realized, with the small samples and fluctuations of the opening frame left behind in favor of more stability. The cold days in the Midwest are less numerous; we now know the teams with a capacity to surprise, and the ones that never really had a shot. That sense of May stability is an artifact of our human desire to demarcate, to divide, and to end and begin things: the real truth is that every day is merely a day before and after another, moving relentlessly toward a finality — a month, a season, a career.

Our monthly divisions are a veil draped over the game to provide meaning where there may be none. Still, knowing the futility of our plight, we’re going to press on with that propensity for order and use the end of April to look back at changes between last month and last season in relation to one subset of data: movement of pitches. I’ll be looking at who had the biggest change in movement for their offerings between last year and this year, and perhaps we can glean some data related to whiff rate, batted ball breakdown, or other peripheral statistics that suit our fancy.

Finally, a reminder: more movement doesn’t always mean better results. It does make for entertaining data and visualizations, however. Today, we’ll go over fastballs, so we won’t have the gaudy swing and miss stuff that we’ll have tomorrow, when we’ll look at breaking balls and offspeed pitches. All stats are farmed from Baseball Prospectus’ PITCHf/x leaderboards. Today we’ll divide fastballs by four-seam and two-seam, as well as starters and relievers. As a baseline, I used a 500 pitch minimum for starters in 2014, and a 100 pitch minimum for relievers.

This one might be stretching it, because Rafael Montero has only made one start this year, working out of the bullpen in his other games. Still, he made eight starts last year, and the Mets envision him in a starting role long-term, so we’ll roll with it. It’s a good thing his fastball has increased in movement this year, as he’s thrown it an incredible 76.1% of the time, something his manager is not entirely thrilled about.

With that added movement, he’s seen an almost 14% rise in whiffs/swing (to a 29.5% mark), which would put him in the top-10 of starting pitchers for the season. To compare, I’ve gone through Baseball Savant’s listing of all his four-seamers to find two that exactly resemble his ones from last year and this year. Let’s see if we can see the difference between them (2014 is on the left, 2015 on the right):

It’s difficult to tell: one and a half inches of difference is hard to see in a GIF. Perhaps it’s my mind playing tricks on me, but I think I can see a little more pep at the end of this year’s offering. After Montero, we have John Danks with his retooled fastball (he’s throwing it over 10% more frequently this year, and it is not as terrible as it was before), then Rick Porcello, who might represent the most interesting case in this group. Porcello has added ½ MPH to his four-seamer, an inch of extra rise, and a 9.2% increase in usage from last year. The result: 6% more swings, and almost 22% more whiffs/swing.

J.A. Happ has added a lot more sink to his two-seamer this year, but it hasn’t done very much for him, as his run value per 100 pitches is -1.07. It’s still early, and his four-seamer has been much more effective, so we can perhaps still chalk up his overall velocity decline to it being early in the season. Let’s compare Happ’s two-seamer from last year to this year (with apologies for the difference in camera angle):

Dillon Gee is also the guy we want to talk about, as his change in pitch usage (more sinkers & sliders, less four-seamers and curveballs) has led to a 15% increase in ground ball rate this season (up to 59.2%). The tweak has worked better so far, as Gee’s FIP (3.88) is close to his career low in 2012 (3.71), and he’s also getting 6% more whiffs/swing on his sinker compared to last year. We’ll see where Gee is at the end of the season, but we can certainly see what he’s trying to do.

Also of note: Jerome Williams is still around and going full sinker for the Phillies, Jeff Locke has completely ditched his four-seamer in favor of all sinkers, and Felix Hernandez has continued with his sinker/curve/change combo from last year that seemed to work so well. There aren’t a lot of surprises on this list: most of these pitchers are well-known for their prowess with the two-seamer/sinker.

Relievers are a little bit harder to gauge, as most have only thrown a limited number of pitches in the early going. I’ve set a minimum of 50 pitches for this year to attempt to limit the number of small sample size fluctuations we encounter. That being said, we have some good names on this list: a lot of young, hard-throwing relievers. And also Kevin Gregg.

Brandon Gomes has been around for a while, used mostly by the Rays in lower-leverage situations and mop-up duty. His whiff/swing rate is up 11% on his four-seamer this year, though there’s still bound to be a fair bit of noise when it comes to these sorts of sample sizes. Let’s compare the 2014 Gomes vs. the 2015 version:

Chris Martin is an interesting case, as he only broke in with the Rockies last year and has great strikeout potential with his big fastball. With his improved command this year, he’s been a surprise go-to in the Yankees bullpen. Kevin Gregg was somehow pitching in high leverage situations to start the season, something his 8.10 ERA/5.53 FIP took care of quickly. The usual, dominant suspects round out the bottom half of the group: Dellin Betances in particular has almost doubled his whiff/swing rate on his four-seamer in comparison to last year, coming in at a ridiculous 40.43% so far in 2015.

Finally, these are the relievers that might not grab the marquees: the sinkerballers who might not find themselves in eighth and ninth inning work, and who generally don’t have the overpowering fastballs of the pitchers in the four-seam category. Some do, like Justin De Fratus, Zach Britton and Fernando Rodney. Britton in particular continues to hone his sinker, as he throws it almost 90% of the time in the closer’s role for Baltimore and has seen his K% increase 14% over last season.

Leaading the pack is Cesar Ramos, who turned his relative success in Tampa into a gig as one of two lefties out of Anaheim’s bullpen. Much like many of the pitchers on this list, his ground ball rate is currently sitting at a career high. Let’s take a look at his comparison pitches:

We can see a trend developing: Tony Watson has increased his sinker use to 74% in 2015. Fernando Rodney’s ground ball rate is at a career-high 62.1% as he also moves mainly to the sinker. These seem to be pitchers who are actively adopting and working on their two-seamers as the basis of their arsenal. And why not: ground balls are good, and living up in the zone with a fastball is risky business if you’re a late inning guy that doesn’t throw really hard. Given the expansion of the strike zone downward in recent years, it’s not a surprise we have a few closers and high leverage pitchers on this list, trying to add more sink to their two-seamers.

Tomorrow we’ll look at breaking balls and off-speed pitches, identifying the pitchers who have added the most spin onto their curveballs. sliders, changeups, and the like.