AL SP Strikeout Rate Surgers — Last 30 Days

As I have been known to do, let’s take our every-so-often look at American League starting pitchers who are currently making a surprise appearance atop the last 30 day strikeout rate leaderboard. Since pitchers change so much more frequently than hitters, whether due to fluctuations in velocity or an adjustment to pitch mix, it’s far more valuable to analyze small sample pitching performance than hitting performance.

After his strikeout rate collapsed last year upon his move to the American League, Mike Fiers has gotten his strikeouts back to where they had been. And he’s even taken it up a notch over the last 30 days, even posting an ERA right about in line with his SIERA. Of course, for the season, his SIERA remains well above his ERA, as his crazy inflated HR/FB rate is being offset by his crazy inflated LOB%. It’s pretty difficult for a pitcher to strand such a high rate of runners when he’s allowing so many homers! But Fiers has somehow managed to pull off that magic act. His velocity trend looks slightly upward, which is how most pitchers’ charts should look as velocity does increase as the season progresses. Nothing to see here. The one change that stands out is a more consistently aggressive usage of his changeup. He has thrown the pitch in the mid-20% range each game over his last four starts, whereas before that, he was up and down, throwing it as infrequently as 9% and as often as 28.4%. And that changeup is, and always has been, his best swing and miss offering. So hey, the change gets the most whiffs, he throws the change more, he gets more whiffs! SCIENCE! Perhaps hitters adjust, but if he continues throwing the change 25% of the time, or so, then his strikeout rate should continue hovering in the mid-20% range as well.

Don’t look now, but Kevin Gausman suddenly owns a 23.5% K-BB% over the last 30 days. And while his results still weren’t that great (4.02 ERA), his overall skills improved significantly en route to a 3.25 SIERA. It seemed like only a matter of time that Gausman would rediscover the ways of a good pitcher again and I had been wondering early in the season why on Earth he wasn’t throwing his best pitch, the splitter, as often as usual. Wellllll kids, since his outing on June 16th, his splitter usage has sat above 20% in six of eight starts, and he was in the teens in those remaining two. That compares with eight starts earlier in the season where he threw the pitch at single digit rates, including a game he didn’t even throw the pitch at all! Throwing splitters = good Gausman. Buy before his owner realizes he’s back.

Funky deliveries are good…for a time. Usually the league eventually catches up (see: Hideo Nomo), but early on, the pitcher is likely to have the advantage. Mike Clevinger has been putting his weird delivery to good use and he hasn’t just been striking out batters over the last 30 days, but all season that he’s been up with the Indians. Amazingly, all three of his non-fastballs have generated SwStk% marks above 20%. I don’t even know if “amazingly” is enough of a superlative. It’s better than amazing…incredible? Naturally, his fastball isn’t any good, but he can’t be perfect. I can’t imagine all his pitches remain this effective, but that he’s had three of them means he has some downside protection.

So Carlos Rodon returns from an arm injury and is now trying to be a three true outcome pitcher — his strikeout and walk rates, along with HR/FB rates, are all wayyyyy above the league average. His current strikeout rate would represent a career best for him, though both his velocity and pitch mix are essentially unchanged from previous years. The difference is easy to spot, the SwStk% on his fastball has spiked from the low-to-mid 6% range to over 9%, while his slider remains elite and changeup decent from a whiff perspective. Sometimes pitchers start throwing their fastballs high in the zone, which would lead to more whiffs, but also more fly balls and homers. We do see a trend of increased fastball location for Rodon, but it’s very small and shouldn’t be enough to validate the pitch’s SwStk% surge. Given his minor league track record and age, I’m willing to give him some benefit of the doubt here, but I’d still bet on his strikeout rate declining a bit the rest of the way.

Pitcher suddenly gains several miles per hour on his fastball, pitcher’s strikeout rate jumps by 9% to 10%. That’s Charlie Morton’s story. Interestingly, while his sinker’s SwStk% nearly doubled last year from the velocity spike, it’s right back down to where it had been previously. So the velocity uptick hasn’t increased the whiffiness of his fastball this year, but perhaps it has boosted the effectiveness of his curve, as its SwStk% sits at a career high. He has also lost some ground balls with his sinker, maybe the better velocity has robbed the pitch of some sinking action, I don’t know. With Dallas Keuchel returning from the DL shortly, the Astros have a rotation crunch. It would be silly if Morton was the one to lose his rotation spot.