Jakob Junis

Position: RP B/T: R/R
Age: 31 (09/16/1992)

2023 Traditional Stats: 40 G, 4 GS, 86 IP, 3.87 ERA, 1.291 WHIP, 4-3, 96 SO, 21 BB
2023 Advanced Stats: 109 ERA+, 26.2% SO%, 5.7% BB%, 3.79 xERA, 3.74 FIP, 3.66 xFIP, 0.7 fWAR, 0.8 bWAR

Rundown

K-BB% is a relatively strong indicator of future pitcher performance. Given that it’s two of the inputs pitchers can control, according to the FIP/DIPs calculations, we can expect pitchers who hold a strong K-B% in T season to perform similarly, if not better, in T+1 Season.

In 2023, the National League Leaders (min. 80 innings) in K-BB% included studs such as Spencer Strider, Zac Gallen, and Zack Wheeler, emerging stars like Jesus Luzardo, Eury Perez, and Hunter Greene, and then there’s Jakob Junis.

Junis was an unheralded starting pitcher during his five seasons with the Royals. However, under the watchful touch of Brian Bannister and Andrew Bailey, he completely revamped his arsenal to emerge as the latest success story out of the San Francisco Pitching Development Program.

Junis served as a swingman for Gabe Kapler‘s Giants in 2022, posting a 4.42 ERA over 23 relief appearances. The following season, the Giants moved him to a relief-only role and reaped the benefits, watching him emerge as a trusted option. His success can be attributed to the subtle, yet effective changes, he made to his arsenal.

In 2023, Junis threw his slider 63% of the time, the highest mark in baseball. In 2022, Fangraphs‘ Kyle Kishimoto looked into the changes Junis made to his arsenal, noting that he employed a slider-heavy approach with the Giants, an approach that was made popular by former Ray Matt Wisler.

He threw his slider often for good reason; it was graded as one of the best in the game. The pitch had a Stuff+ of 117, and Pitching Bot graded it as a 61 (on a 20-80 scouting scale); both marks were among the top 20 in the game. Junis’ slider isn’t truly a slider; pitch classification systems identify it as a sweeper, a pitch that’s made strides in popularity during the last few seasons. Several of the Mets’ recent pitching signees have this offering in common, including Sean Manaea.

By prioritizing his slider, he limited the usage of his ineffective fastball and instead evolved into a slider/sinker pitcher. Maxwell Resnick of BaseballCloud suggested that Junis’ supination made him a strong candidate to eradicate his fastball and instead develop a sinker, a change that the Giants later identified and implemented. In 2023, the change paid dividends as Junis’ sinker ticked up in effectiveness. Its velocity rose to 93.7 mph, a career-high, and its Stuff+ ticked 12 points.

To visualize his change in pitch mix, click here.

Junis’ revamped approach resulted in an impressive 3.87 ERA/3.74 FIP with San Francisco in 2023. Putting aside his arsenal metrics for a moment, there were some other positive traits in his profile. His BABIP ticked 20 points above his career high, and although he allowed 12 home runs on the season, xHR (expected home runs) pegged that he should’ve allowed nine.

Contract 

MLBTradeRumors projected Junis to receive a two-year contract worth $15 million dollars, noting that the Diamondbacks and Padres were among his most likely suitors. Trevor Williams parlayed a swingman role with the Mets into a two-year agreement with the Washington Nationals last winter. Junis could land a similar pact.

Recommendation

Junis served as a multi-inning weapon for Gabe Kapler throughout the season, throwing multiple innings in 29 of his 40 outings. The Mets similarly employed Williams in the 2022 campaign and sorely missed him in 2023. Michael Tonkin signed with the idea that he could fill a similar role, though, Junis would represent a more established profile.

Given the Mets’ openings in their bullpen, I think this is a profile the Mets should target for the 2024 campaign.