J.B. Bukauskas' Heavy Sinker Has Him Primed to Break Out in the Brewers' Bullpen

At the end of last season, J.B. Bukauskas’ future with the Brewers seemed uncertain.

The club exhausted the right-hander’s third and final minor-league option last year, meaning it would not be able to send him to the minor leagues in 2024 without first exposing him to waivers. A crowded bullpen mix and his lack of roster flexibility meant he could soon be moving to his fourth organization in three seasons.

Plenty can change in a few months. With opening day less than two weeks away, Bukauskas looks like someone who could easily impact the big-league bullpen. He was granted a fourth minor-league option due to his injury history, and the injury of Devin Williams opens a spot in the bullpen. He has turned heads in camp, striking out 12 in six innings of work.

Bukauskas is glad he’s still a Brewer.

“I feel like I’ve made some good connections and been able to click with a lot of the stuff I’ve been trying to improve on,” he said. “I really enjoy it here, and I’m really happy to be here.”

It’s taken Bukauskas a few stops to land in Milwaukee. He was a first-round pick of the Houston Astros in 2017, who shipped him to the Arizona Diamondbacks two years later at the trade deadline as part of a package that landed Zack Greinke.

Baseball doesn’t care about prospect pedigree; the game can humble anyone. Bukauskas is no exception. Injuries and poor performance as a starter in the minor leagues prompted a switch to the bullpen. When he reached the big leagues in 2021, he got shelled. In 17 ⅓ innings, Bukauskas surrendered 24 hits and four home runs en route to a 7.79 ERA.

The main culprit was his fastball. Throughout his minor-league career, Bukauskas threw a four-seamer with little ride as his primary pitch. According to Statcast, it had 3.6 fewer inches of vertical ride on average than the typical four-seamer thrown at a similar velocity.

To put it into more conventional scouting terms, Bukauskas’ fastball was flat with no life. When he brought it with him to the majors, opponents blasted it for a .500 batting average and .821 slugging percentage.

Upon the mention of his four-seamer in the Brewers clubhouse on Thursday, Bukauskas immediately interrupted before a question was asked.

“It was terrible,” he blurted out.

Bukauskas suffered a grade two tear of his teres major muscle in spring training the following year. As he worked his way back, he focused on replacing his four-seamer with a sinker.

“I was in a sim game, and I was like, ‘I’m just going to try it because the four-seam was so bad,’” he said.

Bukauskas officially made the switch when he returned to game action that summer. After the Seattle Mariners claimed him off waivers from the Diamondbacks in January 2023, he worked with their personnel to further refine the sinker. The breakthrough came after the Brewers claimed him in April.

“When I came here, it really started to take off,” he said. The induced vertical break on his sinker decreased from 3.1 inches with the Mariners Triple-A affiliate to one inch with the Brewers’ Triple-A team in Nashville. According to Statcast, it averaged 5.1 more inches of sink than the average sinker thrown at a similar velocity.

The lower the induced vertical break of a sinker, the more late diving action it will have as it approaches the plate. By slashing a couple inches, Bukauskas added depth to his sinker that made it more effective.

The difference between the fastballs is obvious. Here’s how Bukauskas’ four-seamer looked in 2021:

This is what the heavy sinker looked like during a late-season stint with the Brewers last September:

Because he no longer needed to worry about his fastball getting crushed, Bukauskas could attack hitters more aggressively.

“It ultimately gave me more confidence to just be in the zone more often and have the ball put on the ground rather than in the air,” he said.

The addition of the sinker had additional ripple effects on how Bukauskas attacks hitters.

It plays well with his slider. Bukauskas added depth to that pitch as well, tacking on five more inches of vertical drop from 2021 to 2023. He can now use both pitches to get under barrels.

“The arsenal plays good together,” he said. “That sink-slide allows you to cover both sides of the plate and keep guys guessing when it’s down.”

While the sinker complements the slider, it forced Bukauskas to shelve his changeup, which received a 70 grade from FanGraphs in 2021 and was viewed by scouts as his best pitch.

After the Brewers acquired Bukauskas, Nashville pitching coach Jeremy Accardo and bullpen coach Patrick McGuff told him to ditch the changeup because the sinker was too similar to it.

“I had the changeup, and it was basically the same shape as the sinker, but it didn’t have very much speed differential, so we just banged it,” he explained.

The sinker-slider mix allows Bukauskas to generate weak contact and swings and misses. His main goal is to induce ground balls with the sinker, but he can turn to the slider for a strikeout when he needs it.

“I’m trying to get the ground balls early in counts,” he said. “If I have the ability late in the count to try to put guys away, I’m still going to go for it. I think the big thing is just keeping the ball on the ground.”

Bukauskas’ new mix helped him post a 2.92 ERA and 2.90 FIP in 37 innings in Nashville last year. He induced ground balls at a gaudy 63.3% rate while running a strong 26.8% strikeout rate.

That same mix is strong enough to be similarly effective in the big leagues. With Williams sidelined for at least the first three months of the season, Bukauskas could have a greater opportunity to establish himself in the Brewers’ bullpen. He could be working some big innings for Milwaukee in a few months.