The Royals’ lefty has come out of left field to become a dark horse Cy Young candidate. What the heck happened?
Kris Bubic has been one of the best starting pitchers in baseball this year.
This is true by just about any metric.
ERA: 1.47 (third in baseball)
WHIP: 1.06 (20th)
FIP: 2.70 (eighth)
fWAR: 1.8 (seventh)
bWAR: 2.8 (second, first in AL)
K-BB% 17.6% (27th)
I could go on and on. But you’re just as capable of looking up the numbers at FanGraphs and Baseball Reference as I am. So let’s do something a little different today.
I recently gained access to the TJ Stats application for generating images summarizing pitchers. If you’re unfamiliar with TJ Stats, you can check out the newsletter here. There’s lots of really good content there, including a recent explanation of how to read the charts I’m about to share with you. I hope you’ll check it out.
As part of my research for this piece, I generated graphics for each of the last four years for Kris Bubic. We’re going to look at them together to see how Kris Bubic has come out of (the) left field (bullpen) to go from a starter barely hanging on in the big leagues to a true Cy Young candidate.
2022
A 5.58 ERA is not good. The 1.70 WHIP and 8.0% K-BB% suggest really was that bad. He finished 2021 pretty well; he had that no-hitter interrupted by the rainless rain delay in Chicago, but he also had a 2.20 ERA in September. But 2022 started bad. He had a 13.14 ERA in his first five starts. That caused him to be demoted to the bullpen for a game, and then to Omaha for a month. He was recalled in June due to pitching injuries, and for the rest of the year he pitched to a much more reasonable, if still not very good 4.75 ERA.
My focus on these graphs are going to be on the most obvious changes he’s going to make over the course of the next three years. His pitch usage as seen in the middle-right graph, and his pitch quality as seen in the bottom part of the graph.
In 2022, Bubic was primarily a fastball, changeup, curveball guy. The changeup was great, but the curveball and fastball weren’t very good. Even worse, Bubic wasn’t throwing the changeup to lefties, so he basically didn’t have a plus pitch to get them out. And that bears out in the stats; lefties had a .457 wOBA against him while righties only managed a .346 wOBA. I say “only”, but that’s still really high, especially for the strong side of a split.
And in the final summary, we can see Bubic was basically only good at one thing: getting his pitches in the strike zone. He didn’t generate chases, whiffs, or weak contact. That’s no way to succeed as a pitcher.
2023
Mike Matheny and Cal Eldred were shown the door in 2023, finally, and things were looking up for Kris Bubic in his very short start to the season. A few things stand out as drastically different here, besides the improved results in a small sample.
First of all, his extension on all of his pitches drastically improved to become well above-average. The extension is important because the closer a pitcher is to the plate when he releases the pitch, the less time a hitter has to react to a pitch. Bubic’s velocities were still low, but he was releasing his pitches close enough to the plate that they were harder to read.
Second, he added a slider. There were rumors Cal Eldred didn’t want him to throw it, but as you can see, it immediately added an element of chase to his arsenal that hadn’t been present before. Especially against lefties, for whom he had had no answer before. You can see he still wasn’t really throwing his changeup to them, but adding the slider seemed to be making a huge difference. Small sample size warnings apply, but the wOBA to lefties dropped all the way to .208, though righties still had a .332 wOBA against.
Combine those two changes and you see his chase rate went up by more than 1%, and his whiff rate jumped a whopping 7%. A much more effective pitcher, indeed.
2024
The WHIP and ERA keep going down, the K-BB% keeps going up.
Of course, this is the season Bubic spent in the bullpen after recovering from Tommy John surgery, but as we can also see, he wasn’t idle just because he wasn’t able to pitch.
The fastball went from a dud pitch that he kind of had to throw, to a true weapon, How? Well, he jumped the average velocity from 91.7 to 93.0 while maintain the extension boosts from before the surgery. He also added about 200 RPMs to its spin rate. It’s still not as hard a fastball as other pitchers have, but he had jumped it from a 46 grade on the scouting scale to a 63. He was able to get players to chase and whiff on it. It still gets hit hard when players do make contact with it, but that’s only two out of every three times the swing at it. Which is insane for a fastball.
Perhaps an even bigger change, though, is the addition of yet another pitch, a sweeper. A sweeper is a lot like a slider, but with more horizontal movement and less velocity. in 2024 he got players to chase that pitch more than half of the time he threw it. They didn’t miss it often, but when they made contact with it, they couldn’t do any damage.
He basically stopped throwing his slider, but the sweeper didn’t just replace it as a weapon against lefties; he could also use it against righties. That got him back into having reverse splits, though he was dealing with both sides of the plate better than ever.
2025 (prior to Sunday’s start)
You all already know how elite his stats have been this year, so we don’t need to go over those. There was some fear in some circles that his stuff would diminish as a starter, and to some degree, that’s been the case. Mostly because he’s had to work his slider and sinker back into his repertoire as he pitches to more hitters at once. However, the fastball, changeup, and sweeper all continue to be deadly weapons.
He still has reverse splits; his two worst pitches are the sinker and slider and he primarily throws them to left-handers. His fastball velocity did drop a bit, but he compensated by adding even more spin to it. Also, the break on his fastball is now two inches better than it was in 2022, leading to a lot more pop-ups. Interestingly, the sweeper still isn’t graded very highly despite having an above average tjStuff+ number and being so effective. Apparently, sweepers can get pretty nasty!
But the end results are what matter, and he’s maintained that elite 30%+ whiff rate. He also pounds the zone, resulting in relatively few walks, which allows him to do the one thing that frustrates fans about staff ace Cole Ragans – pitch deep into games.
Bubic has been absolutely fantastic this season. Some of the credit has to go to the coaching staff. As I noted when we were talking about 2023 Bubic, they benefited him perhaps more than any other pitcher on the staff by encouraging him to make changes where the previous regime seemed to discourage such things. But even more credit has to be given to Bubic for taking their coaching and turning himself into one of the best pitchers in the sport.
It’s been a long road for Kris Bubic, but he’s finally living up to the first-round pick hype from 2018. Hopefully, the Royals will extend him and keep him in Kansas City long term. He’s been my favorite pitcher since basically his debut, but I hope and expect he’s become a favorite for many other fans, too.
I feel like I’m not really doing him justice here, but I have no more words. They say a picture is worth a thousand words, so I’ll leave you with one last image: a GIF representing his baseball savant summaries since 2022.
