Diamondbacks select Dennis Santana, designate Philip Abner for assignment

The Diamondbacks selected right-hander Dennis Santana from Triple-A Reno and designated left-hander Philip Abner for assignment before Sunday's game, the club announced. The move swaps one reliever for another as Arizona continues a three-game winning streak heading into the final six weeks of the season.

What happened

Santana joined the organization on a minor-league deal August 6, per MLB Trade Rumors. The selection adds him to the 40-man roster and the active roster. Abner now enters the seven-day designation window, during which the club must trade him, release him, or place him on outright waivers.

The transaction reshuffles the bullpen depth chart at a moment when Arizona is managing a compressed schedule across three cities. Santana gets his second organization of the summer; Abner faces the roster limbo familiar to relievers on the margins.

Why it matters

The Diamondbacks are chasing a postseason berth with 17 games remaining in August and a September roster expansion on the horizon. The bullpen shuffle arrives as the club prepares for a three-city stretch that begins Sunday at Truist Park against the Braves and continues with a two-game set at Fenway Park against the Red Sox on Monday and Tuesday.

Santana spent most of 2026 with Pittsburgh before the Pirates designated him for assignment in July and released him, per the report. In 41 2/3 innings for the Pirates this season, he posted a 6.05 ERA, though his 4.61 SIERA suggested some bad luck, per MLB Trade Rumors. The report noted that Santana was an effective relief option for Pittsburgh from 2024 through 2025, after struggling with the Yankees early in 2024.

The ground-ball profile has shifted. Santana generated ground balls at a strong rate in recent seasons, per the report, but ran a 29.6% ground-ball rate this year, well below the 41.6% league average. He has also allowed eight home runs this season after giving up only five in nearly 30 more innings in 2025, per MLB Trade Rumors.

The selection reflects the urgency of a club that needs every available arm down the stretch. Santana's familiarity with the National League and recent stint in Triple-A Reno gives Arizona a right-handed option with a track record of success as recently as last season.

The numbers

Santana posted a 6.05 ERA and a 4.61 SIERA across 41 2/3 innings with Pittsburgh this season, per MLB Trade Rumors. His ground-ball rate dropped to 29.6%, well below the 41.6% league average. He allowed eight home runs in 2026 after giving up only five in nearly 30 more innings in 2025.

The SIERA figure suggests that some of the damage was driven by bad luck rather than a fundamental decline. The home-run spike and ground-ball collapse, however, point to a pitcher whose margin for error has narrowed. The Diamondbacks are betting that two weeks in Triple-A Reno and a fresh start in the National League West can unlock the version of Santana who was effective in Pittsburgh from 2024 through 2025.

Where the club stands

Arizona enters Sunday's game at 77-68, second in the National League West and 10 games behind the division leader. The club has won three straight games.

Michael Soroka is the probable starter Sunday against Atlanta's Bryce Elder at Truist Park. The Diamondbacks then travel to Boston for a two-game series, with Mitch Bratt scheduled to face Alec Gamboa on Monday and Merrill Kelly lined up opposite Ranger Suarez on Tuesday.

The bullpen now includes Santana, whose recent big-league experience gives the club a right-handed option for a stretch that includes six games in seven days across three cities. The selection also reflects the reality of a club chasing a postseason berth with September looming and roster flexibility about to expand.

What we don't know yet

The report did not specify whether Santana will be available Sunday or what role he is expected to fill in the bullpen. The club has not announced whether he will pitch in high-leverage situations or serve as a long reliever.

Abner's next destination is also unclear. If he clears waivers, the Diamondbacks can outright him to the minors, where he would remain in the organization. If another club claims him, he joins that team's 40-man roster immediately. The seven-day window runs through the middle of next week.

The report did not include Santana's performance at Triple-A Reno or how many appearances he made there after signing the minor-league deal August 6. That stretch presumably served as an audition for the selection announced Sunday.

What to watch

The seven-day clock on Abner begins with Sunday's designation. If he clears waivers, the Diamondbacks can keep him in the organization by outrighting him to the minors. If he is claimed, the club loses him to another roster. Another club can claim him on waivers within 48 hours, or he can be outrighted to the minors if he clears.

Santana's first appearance will clarify his role. The Diamondbacks are managing a bullpen through a stretch that includes six games in seven days across three cities, and the addition of a right-hander with recent big-league experience suggests the club is prioritizing depth over a specific matchup advantage.

The broader question is whether Santana can recapture the form he showed in Pittsburgh from 2024 through 2025. The ground-ball rate and home-run spike this season point to a pitcher whose margin for error has narrowed, but the SIERA figure hints that some of the damage was driven by circumstances rather than a fundamental decline. The Diamondbacks are betting that two weeks in Triple-A Reno and a fresh start in the National League West can unlock the version of Santana who was effective as recently as last year.

The bullpen now has a new arm, and the clock is running on Abner. The Diamondbacks have 17 games left in August and a postseason race that will demand every available reliever. The swap announced Sunday is the kind of marginal adjustment that can matter in September, when depth becomes the difference between a wild-card berth and an early offseason. Arizona sits 10 games back in the division but remains in the hunt for a postseason spot, and the bullpen depth will be tested across the final weeks of the regular season.