Former Pittsburgh Pirates pitcher Chad Kuhl is off to a hot start in Colorado, but did the Bucs give up on him too early?
I wrote an article on departed Pittsburgh Pirates players that left during the 2021-2022 off-season but left out Chad Kuhl by accident, so think of this as a make-up for that.
The longest-tenured Pittsburgh Pirates pitcher during 2021 was Chad Kuhl. The right-hander made his debut in 2016, leaving only him and outfielder Gregory Polanco the only two players from the 2016 team to make an appearance in a Pirates’ uniform in 2021. Regardless, Chad Kuhl never seemed to find his footing in Pittsburgh and the Pirates non-tendered him this past off-season.
However, now Kuhl is dominating in Colorado. He has a 3.86 ERA, 3.92 FIP, and 1.18 WHIP through 37.2 innings of work. He currently has a very solid 0.96 HR/9 and 8.4% walk rate. It’s not often you see a pitcher struggle, then go to Coors Field and succeed. So did the Pirates quote-on-quote ‘miss’ on Chad Kuhl?
I don’t think you can say the team didn’t give Kuhl a shot to prove himself. Kuhl pitched 439.2 innings with the Pirates from his debut in 2016 up through 2021. Across those six seasons (he only appeared in five because he missed 2019 due to Tommy John surgery), Kuhl had a 4.44 ERA, 4.61 FIP, and 1.42 WHIP. Kuhl struggled in pretty much all peripherals with a 1.21 HR/9, 10.3% walk rate, and 20.8% strikeout rate.
In 2021, Kuhl posted a career-worst ERA at 4.82 while also having a 5.31 FIP and 1.43 WHIP. The last two stats are the second-worst he has put up in a season. Not to mention he had a 1.45 HR/9, 12% walk rate, and 21.5% strikeout rate. In defense of the Pittsburgh Pirates, he was coming off a career-worst campaign and missed time with injury.
So what is the driving force behind Kuhl’s emergence with the Rox? The biggest is a change in arsenal. He’s using his sinker a whole lot more often and is using his fastball sparingly. He also uses his change-up about 10% of the time, roughly a 6% increase from ’21. But another thing is that Kuhl’s stuff just might work much better in Coors and nowhere else.
It should go without saying that Coors Field doesn’t behave like any other ballpark. It sits 1600 meters above sea level, and the air density is 15% less than the average MLB ballpark. In comparison, PNC Park is only 226 meters above sea level. The average humidity in Pittsburgh sits around 78%, but it’s likely higher near PNC Park, given the stadium was built bordering the Allegheny River. Colorado, meanwhile, has an average humidity of about 54%. Even with the humidor, it’s hard to fight mother nature.
I’m not a physicist, but research shows that low-spin offerings work way better in low-density environments like Coors than anywhere else. The Magnus force, which is the force that helps a back-spun fastball ride through the zone and gives it the ‘rising fastball’ effect, isn’t as strong in Coors. Kuhl’s sinker has a spin rate of just 2134 RPM, and his fastball sits in the bottom 26th percentile.
Look at some of the most recently successful Rockies pitchers. German Marquez throws a four-seamer and sinker with sub-2150 RPM. When Kyle Freeland finished 4th in Cy Young voting in 2018, his four-seamer averaged just 2266 RPM with a similar spin on his sinker. Since then, he’s added RPM to his four-seamer and hasn’t come close to his 2018 peak. Jon Gray consistently sits in the 2000-2150 RPM range of spin with his four-seamer and had a 107 ERA+ with the Rockies. Austin Gomber and Antonio Senzentela both are below the 30th percentile in fastball spin. Daniel Bard and Robert Stephenson have found success in Coors as high-spin rate fastballers, but they also average about 97 MPH. Only Marquez has a fastball that averages out within 1 MPH of 95 MPH.
Although Kuhl has dramatically changed his arsenal usage, his stuff might only work in Coors. Low-spin, average velocity won’t work in PNC, but it will in Colorado because of the low air density. Luck has also dealt him a good hand so far. He has just a .179 batting average on balls in play and 85.6% left on base rate. Not even Jacob deGrom had that high of a left-on-base rate during his back-to-back Cy Young seasons. Sure there are a lot of outliers in LOB%, which we discussed with John Candelaria’s 1977 season, but there’s another factor to consider. As for his BAbip, Kuhl likely will regress in that department. No pitcher has had a sub-.200 BAbip in an entire season since integration, and chances are Kuhl isn’t going to be the first guy to do it. There’s a direct link between a pitching staff’s BAbip and a team’s defense. Kuhl’s .179 BAbip is lucky to start with, and the Rockies defense has only been about average this year with 0 DRS, a +.6 UZR/150, and -6 Outs Above Average. Plus, he’s still well below average in limiting hard contact. He ranks in the 32nd percentile of exit velocity and 34th percentile of hard-hit rate.
So, did the Pittsburgh Pirates miss on Kuhl? They tried him in the rotation and eventually the bullpen across five different seasons, and he ended up with just a 95 ERA+. It’s not like the team gave up on him, ala Tyler Glasnow. Kuhl’s stuff should play up in Coors, and he might be closer to a 100-110 ERA+ kind of arm because of it. But the Pirates shouldn’t lose sleep over it, and Pirates fans shouldn’t be frustrated over losing Chad Kuhl and his subsequent hot start to 2022.