There’s always going to be risk in acquiring a 35-year-old starting pitcher. Father Time is undefeated, and Uncle Injury is the #1 contender. The Yankees are taking on both with the signing of Corey Kluber, who will turn 35 in April, and has only pitched 36 big-league innings since 2018. Grains of salt and caveats abound when discussing what we think Kluber can be this season, but I tend to think that his repertoire provides a reason for optimism.
Power pitchers usually have some transitional period as their fastball dies. Yankee fans should know this better than most — we watched CC Sabathia go from a hard-throwing lefty to a cutter/slider reliant fourth starter, who was effective if in short bursts. Zack Greinke has had more success in that transition, moving from a 97 mph fastball in Kansas City to arguably the best junkballer of all time with Arizona and Houston.
Kluber isn’t one of those pitchers though, largely because he’s never really relied on a hard fastball. He hasn’t averaged 94 mph since 2014, and since the introduction of a cutter in 2017, his fastball usage overall has declined in lieu of a cutter-sinker combination, a la Roy Halladay. His last full season, 2018, when he was a five-and-a-half win pitcher, he used that combo to open the count about 70% of the time. The cutter’s high spin rate, 2600 rpm, means it moves vertically much less than the sinker, despite both pitches coming from the same arm slot.
Crucial to the age question, cutters have a habit of becoming the aging pitcher’s best friend. Sabathia used it, Andy Pettitte too, and in general pitchers adopt and vary the cutter’s horizontal movement to maintain effective stuff even as their fastball dims. For Kluber to recognize the value of the cutter earlier in his career and already have a good handle on it before reaching the downturn of the aging curve is a real positive in projecting his performance.
Then there’s Kluber’s not-so-secret weapon, the curveball. He throws it about 20% of the time, hitters manage a .143 wOBA against it, and it dominates the later parts of a plate appearance. It’s Klubot’s baby, and he talks about it as such:
Corey Kluber describing his curveball grip/release (Popular Mechanics). pic.twitter.com/H3p3RABSWv— Rob Friedman (@PitchingNinja) January 18, 2018
In his best seasons, Kluber gets a swing and miss on the curve about half the time. In his merely good seasons, a whiff rate of 40%. In 2019, the injury-shortened season where we saw the first signs that Kluber’s sinker and fastball might be slipping, the curveball still induced whiffs 38% of the time. Again, like the cutter, breaking pitches can age well, and the blend of Yankee analytics with Kluber’s own self-awareness about the pitch is exactly the attitude needed for effective pitching at 35.
Health is the question for Kluber. His repertoire, style and attitude toward pitching should all give us a healthy dose of optimism that he can be effective, especially within the one-year term he’s signed for. If his shoulder is 100%, and he can make 25 starts for the Yankees in 2021, I think you’re going to see some good pitching with the potential for something great. Roy Halladay was terrific at 34 with a similar pitching mix, undone by back injuries. If Kluber’s on the field, he should be a handful for opposing hitters.