It’s still too early to know much of anything. That’s going to stay true for a while. So we’re still going to look for indicators that ought to stabilize quickly, which means fastball velocities remain of interest. Have you grown tired of reading articles about changes in fastball velocity? I have, too! But here is another one of them, just to bring 30 names to your attention. The subject might be tiresome, but the data’s still relevant.

You’ll find two tables. One shows the 15 pitchers with the biggest gains in average fastball velocity since 2016. The other shows the 15 pitchers with the biggest losses in average fastball velocity. I could’ve cut off at 10, instead of 15, since that’s more conventional, but I think stretching to 15 brings more pitchers of interest into the fold. To gather this information, I ignored the FanGraphs leaderboards and went for the PITCHf/x leaderboards at Baseball Prospectus, powered by Brooks Baseball. That’s because the Brooks Baseball numbers have been calculated in the same way year over year, while the numbers on the FanGraphs pages have had a change in source, from PITCHf/x to Trackman. According to Brooks, the average fastball right now is down about half a tick, which is what we’d expect in early April. OK. Onward!

Some points to consider, before we get to the tables themselves:

(1) In general, for a pitcher, gaining velocity is good, and losing velocity is bad. That’s intuitive. There are strong, established relationships between velocity changes and changes in performance. This is why we focus on velocity so much. It’s important!

(2) General rules do not apply to every individual pitcher, specifically. Marco Estrada lost velocity last year, but his ERA- stayed the same, and his FIP- got better. Adam Morgan gained velocity last year, but he wound up with an ERA over 6. Everybody’s different. Everybody adapts differently.

(3) It’s important to understand why velocity might have changed. Not that we can always know. When a pitcher loses velocity, it can be a sign that he’s hurt. Or, his mechanics could be off. Or, he had a cold. Or, it could be intentional! All data requires an explanation. These tables are simply to raise your awareness.

(4) The little calendar on my screen says it’s April 11. The physical calendar on my wall agrees. Velocity takes little time to stabilize, but it *is* still very early. Everyone deserves more time. The following are just pitchers to monitor.

I think we’re ready for table No. 1!

There are some bullpen conversions in here. That’s a natural explanation for why certain velocities would be playing up. Just the other day, Dave wrote about de la Rosa and Bradley throwing gas out of the Arizona bullpen. This reflects Iglesias’ permanent shift to the bullpen — his 2016 numbers were dragged down by his beginning in the rotation. Wilson has relieved. Morgan has relieved. It’s still notable to see which velocities are up, no matter what, but we expect relievers to throw harder. Arizona has two very promising conversions.

Mejia is one start in with the Twins, and that one start was bad. He’s also being compared here to just one big-league appearance a year ago. Might not be too relevant. Bethancourt? He’s actually learning to pitch now, so some velocity gain makes sense. It’s no longer just about his raw arm speed. Miller has been throwing harder since the spring. He’s taken it upon himself to put 2016 in the rear-view mirror, and although he’s pitched just one game, the stuff and the seven strikeouts are encouraging. He’s a major bounceback candidate.

For the Rockies, it’s great to see McGee rediscovering some old zip, and it also helps to have Chatwood playing up. Although he’s yielded 14 hits, he also has a dozen strikeouts in just 47 plate appearances. Nola gaining velocity seems to imply that his arm feels good, after a worrisome stretch in the middle of last summer. Gallardo stands out in here because, for years, he was losing speed bit by bit. His one-start velocity was as high as it’s been since 2011. The Gallardo trade was weird at the time, but this would be a good way for him to make himself look younger.

To the other side of the leaderboard!

McGowan’s early fastball has topped out at 93.6. That’s down two miles from last year’s average fastball, so the Marlins have to have some amount of concern, given McGowan’s extended medical history. Their bullpen is deep, but this is a tough thing to ignore. The next names of real significance, to me: Cecil and Rodriguez. Rodriguez, because he’s the closer for a could-be contender. And Cecil, because he just signed a four-year contract with a could-be contender. Cecil had arm issues last year, and he’s already allowed seven hits in three innings, with a 15 ERA. I supported the Cecil signing and I still tend to believe he’ll straighten things out, but this is an awful beginning.

Buchholz is one start in. He has his own medical history to keep in mind. Conley is one start in. Hill is one start in, and he had a blister issue, so maybe that explains his presence above. Arrieta and Iwakuma are two starts in, so those points are more meaningful. Arrieta says he isn’t concerned, and he threw a little harder in his second start. He also just struck out 10 Brewers in seven innings, so it’s not like he’s gotten hittable. We’ll all just agree to keep track of Arrieta’s velocity and command as we get deeper into the year. Iwakuma didn’t show a velocity improvement in his second start. Although his ERA is 2.25, he’s got six walks and four strikeouts in 12 innings. Iwakuma here is as discouraging as Gallardo above is promising — the Mariners rotation could be their weakness, and Iwakuma has fought shoulder issues before. If he’s throwing 85 or 86, that could be below the threshold of acceptability.

Calendar still says it’s April 11. I guess it’s still April 11. We’ll all learn to know which pitchers we can trust, and which pitchers we can’t. Velocity is just one factor, and all the samples remain small, but velocity still stabilizes sooner than anything else. As such, this post shouldn’t be a complete waste of your time.