One important question that Jed Hoyer and Carter Hawkins must answer this winter is how real Hayden Wesneski’s early success was, and more, how much of a role they want to carve out for him in 2023.
We know that Wesneski was getting results, and that his top-level numbers looked good: 2.18 ERA and 3.20 FIP over 33.0 IP (6 appearances). He had a 25.0% K rate, a 5.3% BB rate, and a 4.5% barrel rate. All excellent numbers.
More importantly, perhaps, Wesneski’s stuff-based metrics were electric. He essentially showcased the best mix of Command+ and Stuff+ in the organization, depending on your source for those numbers.
We saw fantastic feel for a double-plus sweeping slider to go along with plus grades on both the cutter and sinker. The guy has some outstanding pitches.
It bore out in the results, with an exact equal match to both his ERA and xERA (2.18). While those numbers are surely not sustainable, if his true talent level is something more in the range of his FIPs, he’s still a guy that a contending team should want in the rotation.
While readers will know I’m generally an advocate for giving MLB opportunities to MLB-ready prospects, there is one thing gnawing at me in confidently projecting Wesneski’s 2023 success: I suspect the success he had specifically with his four-seam fastball in 2022 is not presently sustainable. The pitch, one I cited as the pitch most in need of development upon his acquisition, was a huge success over the 128 times he threw it during his 33-inning cup of coffee.
Using Statcast, we can see that Wesneski allowed a .120/.158/.200 batting line on four-seamers in 2022. The .158 wOBA he allowed was actually worse than we’d expect from the batted ball data, as his .128 xwOBA on the pitch suggests. In fact, Wesneski’s four-seamer had a run value of -1.8 runs per 100 pitches, a number that would rank top 30 among pitchers with 50 plate appearances ending on the pitch. Most simply put: he dominated with four-seam fastballs.
But this is where we have to begin to consider process over results. Cameron Grove’s pitch grade model rates Wesneski’s four seam as the worst of his five offerings by a substantial margin (the only one to rank below-average). The pitch’s average velocity of 93.1 mph is not special, and neither is the modest ride or cutting movement he’s able to achieve.
Grove’s model estimates that Wesneski’s four seam has an xRV/100 of 0.80 runs allowed (positive is bad in this instance). This runs very counter to the results from his time in the Majors, when his four seam allowed actually had a run value of -1.8 runs per 100 pitches by Statcast’s calculations. And again, his xwOBA on the pitch was actually better than his wOBA (.128 to .158).
Given the gap between results (actual and expected) and the raw qualities of the pitch, I wanted to see if Wesneski and the Cubs pitching team were able to utilize sequencing to play the pitch up.
I looked at every Wesneski four-seamer this year, and noted the pitch that came before it (or, about a quarter of the time, when it led off an at-bat). Perhaps he was tunneling the pitch in an extra special way.
The 29.4 Whiff% on four seamers that come after sliders is notable to me, as is the 33.3 CSW% on four seamers after sinkers. Those seem like the pitches we’d expect Wesneski to be throwing four seams against, and we did see fantastic execution of his game-planning during his Major League sample. But the real thing that jumps out is the .167 overall BABIP, a number that, no matter what development the pitch receives, is not sustainable.
So if I were the Cubs, here is what I’d do. I would regress Wesneski’s 2022 numbers to reflect a worse outcome on the 60 swings that were taken against his four-seam fastball. I would then use those revised numbers – rather than the actual numbers – to project his 2023 performance. In the meantime, I’d be giving Wesneski two pieces of homework for the offseason: 1) a small round of velocity training, in the name of trying to reduce any sub-92.5 mph fastballs, and 2) an attempt at adding a little more cut-ride to the fastball, particularly trying to get that fastball to have less than 4 inches of run.
Hayden Wesneski should be a top 100 prospect, and he should absolutely be someone who gets a lot of big league innings in 2023. But the caveats about believing completely in his 2022 performance do apply, and caution must be taken when planning the roster as a result.