Andrew Saalfrank Emerges as Key Piece of Diamondbacks' Bullpen in 2025
Saalfrank, who just turned 28 a few weeks ago, has solidified one of the eight spots in the 2026 bullpen. Since rejoining the team on July 5th, the lefty has pitched to a 1.16 ERA in 22 games.
The Diamondbacks' bullpen was a key contributor in their 2025 season getting away, but one man has stepped up in the home stretch. Left-hander Andrew Saalfrank has emerged as a key arm in the back of the bullpen.
Saalfrank, who just turned 28 a few weeks ago, has solidified one of the eight spots in the 2026 bullpen. Since rejoining the team on July 12th, the lefty has pitched to a 1.16 ERA in 22 games. Behind that strong performance are strong peripherals, with 17 strikeouts to only six walks in 23.1 innings.
The most impressive part of his resurgence has been a significant reduction in walks, dropping from 9.8% in 2023 to 6.7% in 2025. Combined with a ground ball-leaning profile (47.0% ground ball rate per Statcast), he has the potential to be a solid left-handed setup man.
Saalfrank Has Become a Dependable Reliever in the Late Innings
When it comes to relief work, my favorite stats to use for potential back-end arms are shutdowns and meltdowns. Both metrics are win probability stats for relievers on FanGraphs. A reliever who improves his team's win expectancy in a game by at least 6% earns a shutdown. An appearance that reduces his team's win expectancy by 6% earns a meltdown.
Saalfrank is one of four relievers on the current roster with more shutdowns than meltdowns. He is one of four relievers in the current bullpen with more shutdowns (11) than meltdowns (2). The other three pitchers in the positive this season are Jalen Beeks (14/6), Taylor Rashi (2/0), and John Curtiss (4/2). Of the four, Saalfrank has the best ratio at 5.5 shutdowns per meltdown.
Both his meltdowns came on the same road trip. The first came on August 11th against the Texas Rangers, when he was walked off in extra innings. The other came in Coors Field, where he failed to prevent an inning from collapsing out of control against the Colorado Rockies. Since that road trip, Saalfrank has been tough to score on.
Another unexpected twist has been Saalfrank's ability to get right-handed hitters out consistently. While it's only a sample size of 64 batters faced, he's holding them to a .177 average with 11 strikeouts to two walks. As a late-inning arm, being able to neutralize platoon advantages is critical.
Saalfrank's strong track record under pressure has earned manager Torey Lovullo's trust. That's important when constructing a bullpen moving forward because nothing is more frustrating than watching them blow leads. The one year where the bullpen became dependable, they made a Cinderella run to the 2023 World Series.
Is This Run for Saalfrank Sustainable?
Long story short, no. It's unlikely he'll maintain a 1.16 ERA with a low strikeout rate. His 3.01 FIP, 4.09 xFIP, and 3.44 xERA all suggest potential regression down the road for Saalfrank. However, he can continue to beat the projections with increases in his strikeout and ground ball rates.
The two pitches with the largest gap between actual and expected results are his four-seamer and sinker. The expected metrics (xBA, xSLG, and xwOBA) all attempt to minimize the impact of defense. Those metrics use a hitter's exit velocity, launch angle, and occasionally their sprint speed on certain batted balls.
Four-Seamer: .067 BA/.275 xBA, .067 SLG/.442 xSLG, .059 wOBA/.304 xwOBA
Sinker: .257 BA/.315 xBA, .371 SLG/.514 xSLG, .304 wOBA/.379 xwOBA
Curveball: .152 BA/.166 xBA, .152 SLG/.244 xSLG, .166 wOBA/.206 xwOBA
Better fastball command should improve Saalfrank's results, in terms of the expected metrics on Statcast. The improvement in both his strikeout and walk rates compared to 2023 is an encouraging sign in his development. Moving forward, you want to see the strikeout rate continue to improve from 19.1% while maintaining his strong 6.7% walk rate.
2026 Bullpen
With Saalfrank emerging as one of the top arms in the bullpen, he's a lock to make the club in 2026. He'll likely be the high-leverage or late-inning left-hander out of the bullpen due to his solid track record. That record extends beyond just the regular season, as he was their top lefty in their 2023 postseason run as well.
The other seven spots will be difficult to fill. The team utilized a lot of rookies and journeymen in their bullpen down the stretch. Ryan Thompson may be the only other lock to make the club out of this current bullpen. Roster decisions will come down to the health of certain pitchers.
It's hard to project who else will join Saalfrank and Thompson in next year's bullpen. If healthy, Kevin Ginkel and Christian Montes De Oca are quality candidates. Nabil Crismatt has found recent success with the D-backs of late as an emergency starter, so he's a potential long man option.
The rest of the bullpen will likely have to come through external additions, whether that's free agent signings or trades. The good news is that with all those rookies, they have optionable depth to work with throughout the season, which they might not have had in years past.
