Caleb Kilian, Now With Velocity

I’ve been fascinated by Caleb Kilian for quite a while. Since 2021, to be precise, when he put together a dazzling 80 innings of minor league work for the Giants and then got traded to the Cubs in a deal for Kris Bryant. At the time, Kilian was essentially a lottery ticket, an eighth-round pick in 2019 who was old for his level. But man, those 80 innings were just the kind of innings I like – great command fueling both a pristine walk rate and a ton of strikeouts. I filed a mental note to keep my eye on him: Low-stuff high-command guys sometimes pop with a change of scenery, at least in my head.

That didn’t transpire in Chicago. Kilian got a cup of coffee in 2022 and another one in 2023, but his walk rate ballooned as he reached back for more velo against tougher competition, both at Triple-A and in the majors. And then a shoulder strain cost him half of the 2024 season. He returned for 2025 and found himself in minor league limbo as he transitioned to the bullpen; the Cubs released and then re-signed him due to roster considerations, and he hit minor league free agency after the season. He signed a minor league deal with the Giants over the winter, now as a full-fledged reliever. And that’s where the meat of this article begins.

The early book on Kilian was a standard one: plus command, wide arsenal, but no true out pitch and below-average velocity. In his time with the Cubs, however, that changed. By 2024, Kilian was touching 100 at times, but we graded his command as only average. In other words, his results and scouting report matched: He was throwing harder, but it wasn’t working better.

That’s a long introduction about a guy currently rocking 0.0 WAR in 2026, and -0.1 career WAR. But he’s also striking out 30% of opposing batters so far this year, and he has a 0.75 ERA. (Yes, fine, a 3.88 FIP, a 3.88 xFIP, a 2.67 xERA, and a 3.69 SIERA aren’t quite so complimentary.) And despite a ghastly 15% walk rate, both of our pitch models think that his command has been above average this year. I had to know more.

The key to this new form of Kilian? His fastball. The easiest way to show you what’s changed is with a table:

Yeah, as it turns out, throwing the ball three ticks harder while also adding ride, with the result of making your fastball drop 5.5 inches less on its way home, is pretty good. You’re not supposed to be able to do that! The slower you throw, the more time spin has to add induced vertical break. But Kilian is spinning the ball much better than he used to (his spin/velocity ratio has spiked from 22.5 to 25.0), and he’s turned a formerly mopey fastball into a weapon.

To be sure, it’s a very strange weapon. Batters are making a ton of contact against his four-seamer so far this year. That contact has been quite poor, though, with plenty of no-hope grounders and popups. While a .125 BABIP is clearly unsustainable, the overall power suppression makes sense to me; he’s missing the fat part of the bat quite often. That explains his sterling 2.67 xERA, which measures contact quality probabilistically rather than using actual batted ball outcomes.

And while batters are seeing the fastball well enough to put the bat on the ball frequently, they’re taking it for called strikes roughly 20% of the time, way up from Kilian’s previous career numbers. His old fastball was so tempting that batters couldn’t help but swing. His new fastball is causing them some doubt, and that’s completely changed his game.

Kilian has never thrown a higher percentage of his pitches while ahead in the count. He’s never thrown a lower percentage of his pitches while behind in the count. None of that is particularly surprising – he had a 5.32 FIP, a 6.03 xFIP, and a 9.22 ERA in limited big league action before this year. But he’s also gone from quite poor in these categories to above major league average. His fastball has gone from getting him into trouble to setting him up for success. And after he’s set up, he has a new plan of attack: his magnificent curveball.

Kilian used to feature a slider, a curveball, and a changeup in roughly equal quantities to complement his heater. Working out of the bullpen, however, he’s altered his pitch mix significantly. In 2026, he’s leaning on his curveball to the exclusion of other secondaries; he’s used a curve 30% of the time, a hard slider 14% of the time, and he hasn’t thrown a changeup at all.

That curveball used to be a strike-stealing lollipop. It sat in the mid-70s, and he ran zone rates approaching 50% with it in both minor and major league play, freezing batters early in counts before using other options to get strikeouts. This year, he’s using it as a hammer. He’s throwing it roughly five miles an hour harder and leaving the zone far more often. His zone rate with it this year is a piddling 25%, or 147th out of the 152 pitchers who have thrown 25 curves.

By throwing the curve harder and bouncing it more often, he has transformed the pitch. In the strike zone, the angles don’t play well. Slow curves generally don’t; the lower they’re aimed, the steeper an angle they’re falling at when they reach home plate. That’s fine if you don’t expect batters to swing, of course; the whole point of many looping curves is to short-circuit hitters’ minds into a take. But with two strikes, that’s not happening. On the other hand, when Kilian bounces the curveball, this is happening:

Quite often, in fact:

Quite often:

Those are good hitters swinging at bad pitches. But you can understand what they’re thinking here. They’re in tough counts. They’re guessing, at least a little bit; hitting is hard. This guy throws a really crushable fastball. The temptation to offer at anything that starts on a general trajectory toward the top of the zone must be overwhelming. And then whoops, it’s a big bender, and you miss by a foot.

If that were the only thing going on with Kilian, I wouldn’t be so fascinated by his start to the season. This story is one we mostly know by now. Starter heads to the bullpen, throws harder, profits. When you throw all of your pitches harder and also make them move more, good things generally happen. But there’s one change to Kilian’s game that hasn’t been covered by this, and I wanted to dig slightly deeper. That question: Why is he walking so many guys?

The promise of the soft-tosser-turned-reliever is that he’ll have a better idea of where the ball is going than your average bullpen arm. But Kilian is walking 15% of the batters he faces. That’s generally an unplayable amount of walks, and almost always a sign that the pitcher can’t control the ball at all. That’s not a good description of Kilian, though. He’s running a league-average zone rate and manipulating pitches well enough that our models think his command rates as above average. What gives?

One thing that gives is that all statistics are suspect early in the season. I went back and watched all seven walks he’s issued to get a better idea of what’s going on. One was intentional, and I, too, would have walked James Wood in that situation. Three were long battles with good hitters: a seven-pitch walk to J.T. Realmuto, a seven-pitch walk to Gunnar Henderson, and a nine-pitch saga against Xavier Edwards. Two others were six-pitch plate appearances where he just didn’t have a good sense of how to end things. And one was a miserable four-pitch walk to Trea Turner, just a complete lack of command in a spot where putting the ball in the zone was key.

My take, after watching all of these: Kilian’s game doesn’t line up well with three-ball counts. He’s hit 3-2 counts seven times this year – five walks, one strikeout, and a single. It’s easy enough to understand why: His two pitches are a fastball that never misses bats and a curveball he never throws in the zone. Pick one to throw in a 3-2 count; you’re not going to like either outcome.

Plenty of pitchers with numbers that look like Kilian’s just can’t hack it. They hit a run of tough batted ball luck, and the walks just do them in. You can walk a lot of guys without too many consequences when you’re almost never allowing a hit; when the singles start falling, things fall apart. But in his case particularly, I think there’s a countervailing effect. When he gets behind in the count, he allows better results on contact, just like all major league pitchers. That’s just how the world works; when hitters are hunting instead of reacting, they do more damage.

The thing is, Kilian doesn’t actually allow much contact when he’s behind in the count. That’s because he just walks the guy. It’s almost an approach problem more so than a command problem; he’s perfectly capable of hitting the strike zone (league-average zone rate), but he has to leave the zone to miss bats, and batters aren’t indulging him with a chase when they’re in advantageous counts. He’s throwing the ball in the zone more frequently in even counts (0-0, 1-1, 2-2) than when he’s behind. That’s basically unheard of; the league as a whole throws in the zone far more frequently when behind in the count, of course.

So even after leveling up from minor league curiosity to legit big league reliever, Kilian still fascinates me. He’s a bundle of contradictions. He runs huge strikeout rates with a fastball that never misses bats. He walks the world despite having decent command. He’s steadily climbing up the San Francisco bullpen hierarchy, but still drawing mopup work here and there.

The future here is wildly unsettled. Something has to give. Maybe he’ll give in and start working in the zone more frequently when behind, accepting the inevitable increase in loud contact. Maybe he’ll lean into his slider more, or retool his show-me sinker into something he can use at will against righties. Or maybe he’ll stick with his plan and start getting hit around more. Maybe he won’t be able to turn his four-seamer’s strange profile into anything workable. Maybe the first month of 2026 will be the best stretch of his career.

I don’t think that’s how this will work out, though. Maybe it’s just my 2021 self hyping current Ben up. Maybe I’m being swayed by the feel-good story – former Giants draftee returns to the team at age 29 to get his first big league win and his first regular big league playing time. But I look at Kilian’s newfound array of plus pitches, and his track record of being able to move the ball around the zone, and I see more than just a bulk-inning reliever. I wouldn’t be all that surprised to see him atop the San Francisco bullpen hierarchy by year’s end. It’s an easy enough hill to climb, the early results are promising, and like I said, I just think there’s more here.