How Aaron Boone can get the most out of Isiah Kiner-Falefa’s bat

Like it or not, Isiah Kiner-Falefa is going to be on the Yankees’ Opening Day roster in 2023. Whether he’s going to be in the starting lineup is another story.

In an ideal world, Oswald Peraza or perhaps even an ascendant Anthony Volpe charges out of the gates this coming spring to lay claim to shortstop. In all likelihood, that’s not going to happen. Kiner-Falefa will still get plenty of burn. But the luxury of having Volpe, Peraza, and Oswaldo Cabrera in tow, with the latter two already having reached the highest level, is that this season, rather than giving us 140 games and nearly 550 plate appearances of raw, unfiltered IKF, Aaron Boone now has the luxury of picking his spots with the 28-year-old and treating him like the utility player he really is. Whether he’s a useful utility player depends on where he’s deployed, however.

So I took a dive through some of Kiner-Falefa’s splits to try and narrow down what matchups he might be best utilized for in 2023.

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We can start with the most basic of platoon splits:

IKF vs. RHP: 1445 PA, .264/.312/.344 (80 wRC+), 5.8% BB, 14.8% K
IKF vs. LHP: 609 PA, .263/.323/.355 (85 wRC+), 7.2% BB, 12.8% K

The regular platoon splits — and all of these splits, honestly — should be introduced with the caveat that Kiner-Falefa doesn’t even have enough plate appearances in his big league career to look at trends with any kind of statistical confidence. He enters 2023 with just over 1,800 trips to the plate in the majors, and only 609 against left-handers, when it typically takes a bare minimum of 1,000 against each hand before anything stabilizes.

Even with that in mind, handedness doesn’t seem to have made a tremendous difference for Kiner-Falefa’s success, even if the overall record is slightly tilted in favor of lefties. With a high-contact approach and virtually no power stroke against either hand, that’s not terribly surprising.

That being said, while his slash line looks similar, his batted-ball output is also slightly better against southpaws: He’s put the ball on the ground six-percent less than against same-handed pitchers. On the other hand, the rate stats also don’t tell you everything about the results he got at the plate. Context matters, too. According to Baseball Savant’s run values, Kiner-Falefa has been roughly as (un)productive against each hand cumulatively (-4.6 runs against righties, -4.4 against lefties) despite seeing roughly a third as many pitches against left-handers.

That wasn’t terribly helpful. Let’s look at pitch types. Unfortunately, Savant’s run values don’t demonstrate much in the way of a patter for those, either. Of the 35 individual pitch type seasons over the course of Kiner-Falefa’s career, 32 of them have been between -3 and 3. That means that with just a few exceptions — all of them fastballs — he’s been almost a net neutral against just about everything else. Once again, not super helpful when it comes to playing start-or-sit!

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There is something to that fastball thing, though. You’d think that pitchers would be doing most of their damage with four-seamers, as has been en vogue in recent years, but that’s not the case. Kiner-Falefa has been absolutely dominated by sinkers over the last four seasons: His .281 wOBA and .288 expected wOBA against sinkers are both handily the worst in the league since he reached the majors, as is that whopping -20.5 RV. It tracks: Kiner-Falefa loves putting the ball on the ground, sinkers are great at inducing grounders, and big-league fielders are generally pretty good at turning grounders into outs, especially when you hit them as softly as he does. Let’s give IKF some rest the next time Framber Valdez is on the bump for Houston.

There are other small things to observe for a slight advantage. Kiner-Falefa definitely benefits from seeing starters multiple times in a game, seeing his career OPS rise from .616 to .730 after seeing a starter once. Once a reliever gets involved, however, it’s back to square one, as he has swung at a poor .632-OPS rate the first time he sees a new pitcher. Seems simple: If he starts the game, and you still need offense late in the game, he probably shouldn’t finish the game.

There’s a significant missing piece here in that I haven’t broken down his swing at all, and identifying the specific kinds of pitches and approaches that are going to present a good matchup on a game-by-game basis can depend on that as much as anything else. That being said, neither IKF’s swing nor his approach are terribly complicated. There’s not a ton of breaking down to do: His lack of strength and short bat path mean he’s only able to do any damage when the ball is right down the middle. More than 60 percent of his hard-hit balls the last two years have been in Savant’s “heart” zone, the seventh-highest among 130 qualified batters. He also chases out of the zone at a league-average rate, which leads to a lot of bad contact when you put bat on ball as much as he does. Perhaps there’s a solution involved wherein he only hits against pitchers known to fill up the zone. Just not sinkerballers, I guess.

What does this all come out to? There’s not a super clear answer, but we can approximate something. Maybe start Kiner-Falefa against fewer right-handers. Avoid pitchers who throw sinkers at all costs, and he might have a chance to get it out of the infield a little more. If you still need offense, yank him at the first sign of a reliever. And if it’s one of those pitchers who lives out of the zone because their stuff is just that nasty? Forget about it.

That’s a pretty strict set of limitations, but Kiner-Falefa is a pretty limited player. If 300 adequate plate appearances (and perhaps some defensive replacement innings) can be squeezed out of that, maybe we can even call the whole thing a success. Maybe!