Trio of Top Arms is Holding the D-backs Bullpen Together

If there were an award for Most Injuries to a Starting Rotation in 2024, the Arizona Diamondbacks would surely be finalists in the category.

During Spring Training, this was the team with a projected starting rotation of Zac Gallen, Merrill Kelly, Eduardo Rodriguez, Jordan Montgomery, and Brandon Pfaadt. The D-backs, who’d been forced to have bullpen games during the postseason, headed into 2024 with what appeared to be a fearsome rotation.

That has not been the case.

Rodriguez has yet to throw an inning during the regular season. Kelly has thrown 24.2, Gallen is at 57.1, and Montgomery, who got off to a late start, has not been good (5.71 ERA in 63.0 IP though that’s improving over his last two outings).

The star of the D-backs rotation has been 25-year-old Brandon Pfaadt, who leads all starters with 90.2 IP and a 4.37 ERA.

Actually, it’s Pfaadt and a durable bullpen that spends most games coming to the rescue. And of the D-backs bullpen arms, the best have been RHPs Ryan Thompson, Justin Martinez, and Paul Sewald. That the D-backs are currently 38-40 and just one game out of the NL Wild Card is due in large part to their skill.

It’s worth a closer look at what these three relievers have brought to the D-backs.

Ryan Thompson

The 32-year-old has tossed 31.0 innings in 2023, in that time earning a K% of 19.5%, BB% of just 2.5%, and an HR/9 of 0.58.

In addition, Thompson has a 1.16 ERA (29 ERA-) and 2.79 FIP (xFIP 2.88, which suggests he’s overperforming a bit).

He relies most heavily on his sinker (71% of his pitches) supplemented with a wicked slider (22%).

His four-seam fastball, he goes to for just 7% of his pitches.

Back in October of 2023 when the D-backs were trying to win a World Series, manager Torey Lovullo said of Thompson, “He’s been a savior for us.”

That hasn’t changed in 2024.

Justin Martinez

Martinez’s season has been a revelation.

Last season, he finished with a 12.60 ERA, shuttling between the D-backs and Triple-A Reno. This season, he’s clearly settled in Phoenix.

In 28.0 IP, the 22-year-old has a K% of 25.9, a BB% of 13.8%, and an HR/9 of 0.00. Add to that a 1.29 ERA (32 ERA-) and a 2.72 FIP (xFIP 3.33), and you have one of the most dynamic members of the D-backs’ pen.

Martinez relies primarily on his 100 mph sinker (42%), a new pitch for him this season, and a 90 MPH slider (25%). Add to that a 90 MPH split-finger fastball and a 100 MPH four-seamer, and you’ve got the makings of an elite reliever.

Again, he’s only 22 years old. Look for him to move into the closer’s spot when Sewald’s time is up.

Paul Sewald

Last year, the D-backs bullpen needed stability, a primary reason general manager Mike Hazen traded for Sewald at the deadline. The former Seattle Mariner did not disappoint.

Although he was late to the 2024 season due to an oblique injury, he’s settled back in, picking up where he left off.

In 13.2 IP, Sewald has a K% of 24.5%, a BB% of 6.1 %, and an HR/9 of 0.66. Add to that an ERA of 0.66 (16 ERA-) and a 3.44 FIP (4.38 xFIP), and it leads to one of the most consistent closers in baseball.

Sewald, 34, brings veteran experience as well as a 91 MPH four-seam fastball (64%), a sweeper (35%), and a rare changeup (1%).

But he wields these tools with the accuracy of a surgeon.

Closing Thoughts

Whether the D-backs can return to the postseason remains to be seen, but they are clearly in the conversation. Reports suggest that Gallen will return as early as next week, while Kelly looks to have an August target date. Rodriguez’s ETA remains unknown.

While fellow relievers Joe Mantiply and Kevin Ginkel do their share of the work, the D-backs will look to Thompson, Martinez, and Sewald to maintain their elite performances that keep the team in the hunt.