Jakob Junis Aims for Unpredictability by Emphasizing Glove-Side Sinkers

The Brewers hope that what they saw from Jakob Junis on Sunday was a preview of what they can expect in the regular season.

Junis worked four hitless innings against the Colorado Rockies. The pitch mix he used to get there mirrored the game plan he deployed as a San Francisco Giant last year.

Sliders and sinkers accounted for 50 of Junis’ 56 pitches. The former did much of the heavy lifting, as he turned to it 57% of the time. That’s not far removed from his 62% slider usage rate from last season.

In an age when pitchers are throwing hard breaking balls at increasingly higher rates, Junis remains an outlier by using his sweeping slider as his primary offering. It’s an approach that makes sense for him; the slider grades out as his best pitch by far, and using it more helps compensate for a sinker that was blasted last season for -9 runs relative to average, according to Statcast.

However, Junis still sees a role for the sinker in his arsenal. His vision for that role is another feature that sets him apart from other pitchers.

Many sinkerballers will attempt to bust same-handed hitters inside with the pitch. The goal is to jam the hitter and produce weak contact. Bryse Wilson and Joel Payamps are hurlers who used this strategy to an extreme in 2023.

Junis, meanwhile, focuses more on the opposite side of the plate. Last year, the majority of sinkers he threw to righties were of the back-door variety on the outside corner.

Junis continued his intentional emphasis on the glove-side sinker on Sunday. One of his goals for 2024 is improved execution of the pitch.

“Anybody that throws sinkers, it’s a lot easier to get it to run arm-side. I think it’s much harder to pick your lane glove-side down and away and stick it and get the ball to come back and stay there without leaking over the plate.”

Junis’ sinker was hit hard when it leaked over the plate. Opponents feasted on sinkers across the strike zone, but he did find (fleeting) success when tucking it into the outside corner of the plate.

Pitches don’t exist in a vacuum, though. Part of the cat-and-mouse game between pitcher and hitter is creating deception and keeping hitters from sitting on pitch types and locations.

“It just opens up everything for me,” Junis said of the glove-side sinker, which he believes fulfills those aforementioned purposes in a couple of ways.

First, it means hitters have to think about hard stuff on both sides of the plate rather than waiting him out until they get an arm-side sinker.

“I can choose to go in [to righties]. I’m not forced to go in because that’s the only place I can throw it.”

Second, it plays well off his slider, which Junis typically locates further away from his glove side.

“I think it’s harder for them to guess what’s coming,” he said, keeping hitters off balance with the pairing. “You’re making X’s. One’s going this way; one’s going that way. As much as I can move the ball, the better.”

Barring improvements to the shape of the pitch, Junis’ sinker is unlikely to be a valuable pitch on its own. However, if it’s a roughly average pitch in isolation that makes his slider better, that bodes well for his production on the mound.

The Brewers will hope that’s the case in 2024. In 2022, the sinker graded out at a palatable -1 run value. The expected opponent wOBA on the pitch last year (.364) was much closer to that of 2022 (.348) than the actual .493 mark opponents posted against it. That implies Junis’ sinker was closer to average than awful based on the kind of swings and contact it induced.

Pat Murphy remained coy about Junis's specific role, instead focusing on his value as a stretched-out arm who can start or cover the middle innings.

Regardless of when Junis delivers bulk outs in games, those outs will be a key piece in Murphy’s puzzle of filling innings this year. For Junis, the glove-side sinker will be part of that process.