Spencer Schwellenbach's Fastball Got Better. What is Brandon Pfaadt Doing?
Spencer Schwellenbach, Brandon Pfaadt, Yoshinobu Yamamoto
Braves Spencer Schwellenbach couldn’t have asked for a better start to the season (14 IP, 14 K, 5 baserunners, 0 ER). What jumps out is how good his four-seamer looks. He averaged 96.1 mph last season with just 13.4” vertical break from his 5.5’ release. This year, he’s averaged 2.5” more vertical break from the same release height (15.9”). His ball is “rising” more in its way to the plate. His ~2.5” jump in extension and higher arm angle are helping him create this carry on its way to the plate. The vertical approach angle of his fastball has gone from -4.7° last year (average) to -4.1° this year (very flat). TJ Stats’ Stuff+ pushed the pitch from a 100 to a 108 in grade (average to above-average), a considerable increase. 📈
His approach has changed as well. Part of that “flatter” VAA is Schwellenbach locating his fastball up-and-away more to lefties instead of middle (see below). This has more than tripled the whiff rate on the pitch, although we’re still in small-sample territory. His four-seam usage to lefties has ballooned from 28% to 42%. To righties, he’s pulled down his four-seam usage despite the improvement in shape and more than tripled his sinker usage to 34%. I hesitated to believe in Schwelly this offseason, but his changes look fantastic, especially given my thought that he’d have to go full-on slider to avoid damage on his four-seamer. I might have to eat crow on this one. Even if his fastball gains regress, the approach shift to righties is the correct move.
DBacks Brandon Pfaadt has made some notable changes. He’s throwing from a higher slot, which has caused his four-seamer to pick up ~2” of vertical break. He had a 5.6’ release height last year (lower than average) and has a 5.9’ release height this year (slightly higher than average). Arm angle confirms he’s up about 4 degrees. I think anything 4 degrees or greater is worth pointing out. Fluctuations around 2 degrees are more standard start-to-start variance. 🐍
The vertical approach angle of his fastball (VAA) is down a lot (.5°). This comes from a head-scratching change in location. He’s targeting his fastballs down to either handedness of hitter. I’ll show the more drastic change below, which is versus left-handed hitters, where he’s peppering the bottom of the zone. He’s lost almost all of his swing-miss on the pitch (no surprise). This is an odd one to me, especially given the majority of damage he allowed on his four-seam last year was in the exact spot he’s now throwing it.
The good nugget here is that he has a new(?) curveball, or the intent on the pitch is way up relative to his fastball. It’s 3 mph harder than his curve last year, sitting ~84 mph with 4” more vertical break (less drop) and 5” less sweep. Despite the big movement loss, the velocity gain is enough for TJ Stats’ Stuff+ model to like this curveball better, giving it a 104 compared to last year’s 100. It’s a lefty weapon that should take some sweeper usage away from his mix.
Dodgers Yoshinobu Yamamoto increased his vertical break from his first state-side outing of 2025, where he showed increased carry from 2024. He averaged 14.5” vertical break last season. He averaged 16.3” in his March 28th outing and 17.4” vertical break yesterday. This happened all while maintaining the same release height and extension, implying that something changed about his grip? Maybe his thumb position on the ball? To my eye, his grip looks the same year over year (from pictures). Is there a chance the ball is different this year, causing guys to pick up vertical break? Year-over-year four-seam shape is up .5” despite the same release metrics. But the shape does line up with April 2204. ⬆️
I’m fascinated to see how much better the pitch plays or whether he returns some of these vertical break gains. Dodgers still have him not elevating the pitch, but I wonder if they become more liberal with elevation given the improved shape. TJ Stats’ Stuff+ has the pitch jumping from a 94 to 105, below average to above-average pitch.
I’ve noticed more carry on 4 seamers so far and that could indicate a return to 2019ish balls.
Yamamoto’s fastball improvement continues to be encouraging. He’s already had 2 starts this year averaging 96+ MPH on his 4S. Looks like he’s continued to drop the arm angle on his splitter to add horizontal break too.