Amidst a rebuild, the Arizona Diamondbacks are finally seeing the fruits of their labor. Led by promising starters Zac Gallen, 2.54 ERA in 184 innings, and Merrill Kelly, 3.37 ERA in 200 1/3 innings, and backed offensively by a quartet of promising young outfield talent, Alek Thomas, Daulton Varsho, Jake McCarthy, and Corbin Carroll, the D-Backs are quickly re-entering a competitive window.
However, the Diamondbacks’ bullpen is still falling flat. After signing Mark Melancon to a 2-year, $12MM contract ($5MM mutual option for the 2024 season, $2MM buyout) and Ian Kennedy to a 1-year, $4.5MM contract ($4MM club option for the 2023 season, $250K buyout), the D-Backs’ pen posted the sixth-highest ERA (4.58), the eighth-most blown saves (27), the lowest strikeout rate (19.7%), and allowed the third-highest batting average (.254). Veterans Melancon and Kennedy did not fare much better. Melancon pitched to a 4.66 ERA in 56 innings with a paltry 14.2% strikeout rate and a career-worst 43.2% ground ball rate, while Kennedy pitched to a 5.36 ERA in 50 1/3 innings with a weak 19.0% strikeout rate and an extremely low 24.4% groundball rate.
However, the breakout of lefty journeyman Joe Mantiply was a bright spot among an otherwise weak bullpen performance. Mantiply, a former 27th-round pick from Virginia Tech by the Tigers in 2013, reached the majors for a quick stint in 2016, before shuffling around various minor league teams and undergoing Tommy John surgery in 2018. He signed a minor league deal with Arizona in 2020, making another short appearance in 2020 before eventually joining the team in a more long-term fashion during the 2021 season, in which he pitched 39 2/3 innings to a 3.40 ERA with opponents hitting a strong .292/.358/.448 against him.
In the 2022 season Mantiply, who is controllable through the 2026 season, improved his 2021 numbers. Pitching to a low 2.85 ERA in 60 innings with a solid 25.1% strikeout rate, a sparkling 2.5% walk rate, and missing hitters’ barrels (99th percentile for Chase Rate, 94th percentile for Barrel %), the 31-year-old earned a trip to the All-Star game in his second full season. Left-handed hitters have found limited success against Mantiply, slashing a poor .247/.297/.282 against him, while righties are hitting a slightly better .260/.272/.404. The unsightly .252 combined average may be cause for concern, however, Mantiply is tied for the 27th lowest Hard Hit%, among relievers to pitch 50+ innings, and is in the 89th percentile for Average Exit Velocity.
The Diamondbacks will likely look to address their bullpen again this offseason, but with a high-leverage lefty reliever in Mantiply, they will have one less bullpen spot to fill.