The Best pVals in 2023: Fastball Edition Part Two

pVals are a topic of debate among pitch-level data masterminds. One side may consider them useless. Good pitches get hit and bad pitches get taken for strikes and pVals don’t explain any of that. On the other side, people like to know what actually happened. If a splitter left in the middle of the zone gets a called third strike when it probably should have been mashed for a home run, then pVals still credit the pitcher. The strikeout is what actually happened.

Keep in mind as you peruse this season’s best fastballs just that; pVals aren’t perfect. You’ll read about Chris Bassitt’s sinker and think, Chris Bassitt is a clear candidate for being drafted, but read on and you may back away from that stance. pVals help us understand what occurred, but take caution when using them to predict what will happen. Confused? Let’s just watch some GIFs.

Part one of this installment looked at four-seam fastballs and cutters. Part two will focus on sinkers and splitters.

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wFS – Splitter RAA

• Fake Winner: Kodai Senga 6.6
• Real Winner: Taijuan Walker 3.8
• Runners up: Kevin Gausman 3.4, George Kirby 1.9, Logan Gilbert 1.6

There were only seven qualified pitchers who threw a splitter in 2023 and, depending on who you ask, Senga wasn’t one of them. However, PitchInfo classifies his “Ghost Forkball” as a splitter and that’s the measurement I’m using for this pVal series. Call it a forkball, call it a splitter, just don’t call it easy to hit. According to statcast, the pitch had a .103 expected batting average while its actual batting average was a cold .110. Here’s a look at Senga dropping the splitter in on Jake Burger:

It really just drops right out of the sky, doesn’t it? Here’s the view from a left-handed batter’s perspective of Senga’s arsenal:

Notice how similar the four-seam fastball (red) and splitter (teal) look coming out of the hand. Again, it’s hard to compare Senga’s pitch with others like it from a movement profile, because of its unique designation. Even Stuff+ lists it under it’s own “Stf+  FO” and it scores an 83. What’s interesting is that Matt Carasiti of the Colorado Rockies is the only other pitcher (regardless of IP) who throws an “FO” according to Stuff+ and his pitch actually rates higher than Senga’s at 89. Here’s a look at that pitch:

That’s some serious late break. It’s possible that, at this point, I’ve worked my way into a hole. They say the first rule of thumb to follow when you find yourself in a hole is to stop digging. Let’s give Senga the fake win and move on to Taijuan Walker.

2023 marked the first season Walker threw the splitter more than any other pitch. His four-seam fastball usage has been on the decline since 2019. The splitter, in 2023, garnered only a .257 wOBA and paired very nicely with his sinker and four-seamer. Though his 2022 version of the pitch performed significantly better from a run value perspective, 2023’s version got the job done too.

Walker’s splitter was much more likely to result in a ground ball out than anything else and hitters only got to it for a .205 batting average. The location was really good when you look at his statcast heatmap, but he actually placed fourth out of five qualified pitchers who threw a splitter by Location+. It’s hard to say why that may be, but my guess is that he left a few too many splitters in the zone over the course of the season but got off easy. We, again, see how pitch model scores can differ from pVals in the case of Walker’s splitter.

wFS/C – Splitter RAA/100

• Winner: George Kirby 1.10
• Runners up: Dylan Cease 1.00, Kodai Senga 0.99, Taijuan Walker 0.40

In 2023, George Kirby saved just over one run for every 100 splitters he threw. That may not seem like much, but when you consider the pitch earned a league average 17.4% (PitcherList) swinging strike rate, you understand that it’s strength does not come from volume. He saved this special weapon for only the luckiest of left-handed batters and it was his best “PutAway” pitch. Just look at how well he located it to all batters:

Baseball Savant

For a control artist like George Kirby to have a putaway pitch he can go to that keeps hitters off balance is impressive. It does so by being just different enough from his changeup, which he practically dropped in 2023, and distinctly different from his slider.

Baseball Savant

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wSI – Sinker RAA

• • Winner: Chris Bassitt 24.2
  • Runners up: Jordan Montgomery 15.4, Framber Valdez 12.9, Sandy Alcantara 12.0

Let’s appreciate a pitch that performs below-average when it comes to ground ball rate, Chris Bassitt’s sinker. His 2023 version of the pitch dropped to 53.6% GB% compared to 2022’s 63.8%. The league average is around 55.5%. Yet, somehow, Bassitt’s sinker outperformed everyone else’s pVal. How? Take a look at some of the metrics that defined the pitch, which I’ve pulled from Bassitt’s PitcherList player page:

I am a little perplexed by this pitch given Bassitt locates it directly in the zone, it has a below-average ground ball rate, it is not significantly different in its movement profile compared to others like it and it’s his most utilized pitch. My guess is that it’s due for a little regression, especially considering Statcast’s expected metrics are higher than his actuals.

Yet, looking at just one example of a called strike, you can see that the late drop on the pitch causes a pause:

Will it be good again in 2023? Well Stuff+ grades it as a 92 which is 17th best among qualified pitchers, so do with that what you will.

wSI/C – Sinker RAA/100

• Fake Winner: Freddy Peralta 6.51
• Real Winner: Justin Steele 3.99
• Runners up: Chris Bassitt 1.96, Pablo López 1.96, Dean Kremer 2.95

Cutting back from volume to efficiency, Freddy Peralta jumps to the top. Peralta’s score of 6.51 is the largest of any qualified pitchers per 100 value. The next highest was Kyle Bradish’s curveball per 100 pitches thrown at 3.97. For every 100 sinkers, Peralta threw he saved 6.51 runs. That’s impressive. Yet, we once again find ourselves in a pitch categorization hole. Statcast does not give Peralta a sinker and PitchInfo does. But, if we go back to 2021, we can see that statcast was then defining Peralta as throwing a sinker, though it was dangerously close to his four-seamer in its movement profile:

Baseball Savant

It’s likely that PitchInfo is misclassifying a few four-seamers as sinkers and those pitches did really well from a pVal standpoint this season.

Let’s drop Peralta from this analysis and focus on Justin Steele. Don’t call him a two-pitch pitcher, even if he did throw three out of his five pitches less than 2% of the time each. He only threw 48 sinkers in total, he kept hitters from squaring it up and gave up only three hits. It was an effective pitch likely because it was thrown so little. I’m not sure, based on the location map from Savant below, that Steele has great control of the pitch, but it was effective nonetheless.

It’s always good to have a pitch that can be thrown with a high likelihood of getting an out, and Steele had that pitch. But, his season was defined by his four-seamer…I mean cutter…I mean…dangit! Another classification issue is upon us. Whatever it is and whatever you want to call it, it was decent. Just decent. But, that’s the beauty of looking at the run value of a pitch for every 100 thrown. It brings pitchers to the forefront.

Have some fun clicking around PitchInfo’s pVals and maybe you’ll find something you didn’t know you needed to know. In next week’s article, I’ll whiff away at 2023’s best sliders, curveballs, and changeups. See you then.