BRADENTON, Fla. -- Chad Kuhl is one of the more compelling storylines in Pirates camp this spring. After missing 2019 recovering from Tommy John surgery, it's unknown if he will get a chance to start again or if he will transition to the bullpen. Obviously he could provide more value as a starter if he is cleared for the role, but after an up and down beginning to his major-league career, one could argue he would be better off coming out of the bullpen, regardless of what his bill of health says.
Kuhl was fine in his first three years in the majors, recording a 4.37 ERA, 4.30 FIP, 95 ERA+ and a 2.3 WAR over 61 starts. All told, that comes out to being a slightly below league average starter, so the fourth or fifth guy in the rotation. There's nothing wrong with that, but with four spots seemingly taken by Chris Archer, Joe Musgrove, Trevor Williams and Mitch Keller, and a couple guys in the mix for the fifth spot already, like Steven Brault and Derek Holland, it does raise the question if he can leapfrog enough people to get a rotation job. He has the stuff, but it hasn't all come together.
And then there is the lefty problem.
Kuhl has a pretty bad track record against lefties. Those southpaws have recorded a career .370 wOBA against him, the sixth worst among starting pitchers who have faced at least 500 lefty batters since 2016. Of the five ahead of him, three are effectively out of baseball (Ubaldo Jimenez, Doug Fister and Chris Tillman). It's not good company to keep.
I also wrote a Mound Visit about Kuhl back in October. In that piece, I wrote about how he has a rare combination of elite velocity and breaking ball spin, something Gerrit Cole and Charlie Morton also had, but Neal Huntington/Clint Hurdle/Ray Searage could not tap into. That doesn't mean Kuhl will break out and become a Cy Young contender like those two, but it does suggest that he can be more than a back of the rotation starter. He has not pitched as well as the sum of his parts would suggest he could.
I'm going to hit similar beats today that I did in that first Kuhl Mound Visit, but when talking to him at Pirate City, working on a piece about his recovery, he started to bring up those same beats. About how he started to change his pitch mix during his final starts preceding the injury. About how he recognized he had great spin but wasn't using it enough. And most importantly, how he could finally retire those darn lefties.
Kuhl knew he had a problem. It's hard to ignore it when the other team would start five or six lefties every time you were on the mound. Perhaps worst of all, he was predictable.
"I was so fastball heavy, especially to lefties," Kuhl was telling me. "I just didn't have many weapons to attack left-handed hitters. I had some sink, but that was really it. The changeup was always come and go."
Let's look at Kuhl's pitch selection against left-handed batters per year.
In 2016, basically all he offered was sink, like he said. In 2017, he relied on the sinker less, but basically traded one fastball for another, throwing more four-seamers. He also rediscovered his curve that season and started throwing it more regularly in 2018, but he also offered the sinker more that year as well.
But let's take a deeper look into 2018. When the year started, Kuhl attacked lefties the same way he always had, with his sink. It didn't work, and he recognized this.
Let's focus on just his sinker and slider. In April, he threw his sinker roughly twice as often as the slider. In May, it was almost three times as much. But in June, he threw the two pitches the same amount. He also threw more four-seamers than sinkers that month for the first time that year.
Kuhl was roughed up in his penultimate start in 2018 and left after just four innings in his final outing of the year, but before then, he was in a groove. He believes the different pitch mix was a big reason why.
"[Throwing more breaking pitches] helped me a lot, especially to left-handed hitters," Kuhl said. "Especially when they started stacking left-handed hitters. My left-handed splits got way better when I started throwing less sinkers, more four-seamers and breaking stuff.”
Let's see how that translated into results against lefties.
Throw away that first data point in 2016 because it was only one start. Besides that outlier, June 2018 was the second best month he ever had against lefties in his career, going by wOBA (.329). Granted, a .329 wOBA isn't great. It's average, but that's 50 points lower than it was in most of the other months of his career. A guy who can consistently hold his own against lefties and give righties fits is a good pitcher.
Of course, Kuhl can't live on junk alone. That velocity is special, but it's hittable if thrown too often. It seems like all the pieces are there. Kuhl started making the change last season and has had this stewing in his head for a year and a half. The coaching staff is encouraging player feedback, and even if they weren't, a revitalized analytics staff and data-savvy pitching coach Oscar Marin have to know Kuhl wasn't being used properly.
Assuming he does get the all-clear to start, it seems safe to say it will be a different Chad Kuhl than the one we saw throughout most of his career. One that can get lefties out.
Stats and graphics courtesy of Baseball Savant. Additional stats from Baseball-Reference.
MORE MOUND VISIT
Feb. 17: How Stratton became a spin doctor
Feb. 5: Getting most out of middle infield
Jan. 31: Can Bryan Reynolds play center?
Jan. 29: Five outfielders to replace Marte
