Has Kris Bubic Made the Leap?

Kris Bubic
Darren Yamashita-USA TODAY Sports

Last year, Brady Singer enjoyed a breakout season on the mound, making him a rare success story for a Royals development team that has squandered a ton of young pitching talent in recent years. They haven’t had trouble graduating pitchers into the majors; the problem has been helping them grow once they get there. So far, only Singer has made a true impact on the big league club, with fellow 2018 first-round picks Jackson Kowar, Daniel Lynch, and Kris Bubic struggling in their limited time at the highest level. But if his first two starts this year are to be believed, Bubic might be joining Singer in that breakout tier.

Bubic’s start to spring training was delayed due to some lingering shoulder soreness, which meant his spot in the rotation was up in the air until just before Opening Day, when Lynch was shut down from throwing with his own shoulder issues. In 10.1 Cactus League innings, Bubic struck out 15 to go along with seven walks, but in his first start of the season on April 4 against the Blue Jays, he allowed just two runs in five innings of work, giving up seven hits and one walk with four strikeouts. That’s a good outing against a tough offense, particularly one loaded with right-handed mashers against the lefty.

Bubic’s second start on Sunday was the real eye-opener, though: six scoreless innings against the Giants with just two hits, no walks, and nine strikeouts on his ledger, matching a career high. He had never earned more than 17 swinging strikes in a single start; he racked up 19 on Sunday and accomplished that feat in just 76 pitches. That 25% swinging-strike rate was easily the highest of any appearance in his career to go with a 43.4% CSW rate, also his best in any start.

Bubic looks like an entirely new pitcher, too. His velocity has increased across the board, his release point is completely different, his changeup has a new shape, and he introduced a new slider to his pitch mix. That’s a lot of things to track.

When a pitcher completely overhauls their repertoire like Bubic has, how do we know if their adjustments were the right ones? With a deeper understanding of how a pitch’s physical characteristics contribute to its success, we can rely on pitch-level modeling to gain quick insights into how a pitcher is evolving his arsenal. Luckily for us, FanGraphs has a new tool to help us evaluate individual pitches and pitchers: Stuff+. Developed by Eno Sarris and Max Bay, Stuff+ (and its relatives Location+ and Pitching+) attempts to quantify the quality of a pitch using only its underlying physical characteristics. Stuff+ quickly becomes reliably predictive — in under 100 pitches — and is extremely sticky year-to-year. That reliability means that it’s sensitive to changes in a pitch’s characteristics, making it an excellent tool to evaluate a pitcher this early in the season.

Here’s how Stuff+ views each of Bubic’s pitches through his career:

Kris Bubic, Stuff+
Pitch Type 2020 Stuff+ 2021 Stuff+ 2022 Stuff+ 2023 Stuff+
Fastball 75 75 81 101
Changeup 113 84 80 83
Curveball 103 82 77 74
Slider N/A N/A N/A 126

Bubic’s lack of raw stuff was consistent before this season: His fastball has been mediocre, and his two secondary offerings weren’t much better. The reason his heater is grading out much better this year is simple to discern:

The velocity on his fastball ticked up late last year, but it’s reached a new high in 2023, up to 93.1 mph. That extra tick on his four-seamer gives him a bit more margin for error on a pitch that had been hit hard in years past. But the extra oomph isn’t the only thing different about his fastball. Here are its relevant characteristics over the last three seasons:

Kris Bubic, Fastball Characteristics
Year Velocity V Mov H Mov Spin Axis Spin Deviation Active Spin
2021 90.9 7.9 3.5 10:56 8.2 91.1%
2022 91.9 8.7 4.3 10:52 9.0 94.3%
2023 93.1 8.6 2.8 11:00 14.7 86.0%

Bubic has lost a bit of arm-side movement on the fastball despite also shedding some spin efficiency; without as much backspin contributing to its movement, you’d expect it to lose vertical movement, not horizontal. Instead, he’s maintained the pitch’s ride despite the spin inefficiency. That probably has something to do with the fact that he’s throwing it around three inches closer to the plate, with a release point around an inch or two lower than before. That additional extension helps the fastball’s velocity play up, and the lower release point is creating a flatter plane for it.

Kris Bubic, Additional Fastball Characteristics
Dates Extension Vertical Release Point Avg Vertical Location VAA
2021 6.6 5.7 2.69 -5.0
2022 6.6 5.7 2.78 -4.8
2023 6.9 5.6 3.15 -4.1

The other aspect that’s helping Bubic flatten his approach angle is location. He’s elevating his four-seamer more than ever, finally taking advantage of the ride he’s able to impart on it.

A harder, flatter fastball is definitely a good thing, and Stuff+ is picking up on all of those changes. Through Bubic’s first two games this season, the pitch is running a 27.3% whiff rate, a career-high for him. Opposing batters have collected five hits off the heater for a .464 wOBA, but his xwOBA on contact is just .308. It’s still too early to discern anything from his results — he’s only thrown 65 fastballs so far this year — but the initial returns are promising.

Like the rest of the pitches in his arsenal, Bubic’s changeup has also gained velocity, and while that’s normally not a good thing, he’s maintained a 10-mph differential between it and his fastball. More importantly, he’s shifted the shape of his slow ball to further differentiate its movement profile from his heater; the changeup is dropping an additional two inches, and the loss of arm-side movement on his four-seamer has made that gap wider. Stuff+ isn’t as impressed with the adjustments to this pitch, but the results have been fantastic so far: a 46.4% whiff rate, with eight swings and misses on it in his first start against the Blue Jays and their righty-heavy lineup.

Bubic’s changeup has always been useful to keep right-handed batters at bay, but he’s struggled badly when holding the platoon advantage; left-handed batters have put up a .405 wOBA against him during his career. To combat this sizable reverse split, he introduced a slider into his repertoire this season, something he had toyed with over the past couple of years but had never actually thrown in a game until this spring. He explained that process in an early March interview with Anne Rogers of MLB.com:

“I think I have a really good idea of what I want [the slider] to look like. It’s something I wanted to implement the past couple of years, but now, given the rest of my arsenal and how the pitches work with each other, I think I have a much better idea of what the shape needs to be, what the velocity needs to be and how it fits into my arsenal.”

Simply put, Bubic’s new breaking ball gives him a fourth pitch to keep batters guessing, and one he can use to attack left-handed batters. It also gives him a pitch in a third velocity band, since his changeup and curveball sit pretty close together around 81–83 mph.

The pitch isn’t exactly a sweeper — it only has nine inches of horizontal break and is thrown a little harder — but it’s been an effective addition to his arsenal. He’s only thrown 16 of them between his first two starts and has already collected five whiffs on nine swings (a 55.6% rate). Ten of those sliders have been thrown in two-strike counts, showing his confidence with it when he needs to get a swinging strike. Stuff+ loves what it sees in this pitch, likely due to its above-average break and good velocity. Here’s what it looks like in action:

Seven of those 16 sliders that Bubic has thrown have come against right-handed batters; he’s actually collected two strikeouts with the pitch against opposite-handed batters already. Sixteen pitches is less than 10% of his pitch mix so far this season, but as he continues to gain a better feel and confidence with the slider, that number should increase as the season progresses.

Going from three below-average pitches to a solid fastball, a plus slider, and a changeup that might be underrated by Stuff+ if the early results are to be believed is an incredible transformation from Bubic. Entering his fourth season in the big leagues, he looks like he’s finally found the right adjustments to unlock his potential. The newfound swing-and-miss stuff is a huge differentiator that should raise his ceiling considerably. It’s only been two starts, but everything seems like it’s pointing towards a breakout year from Bubic.

Jake Mailhot is a contributor to FanGraphs. A long-suffering Mariners fan, he also writes about them for Lookout Landing. Follow him on Twitter @jakemailhot.

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1 year ago

Excellent read. Saw Bubic against the Giants over the weekend, couldn’t believe the improvement