The Diamondbacks placed Walston (elbow) on the 60-day injured list Sunday.

EDGE Analysis

It was announced in mid-March that Walston will require Tommy John surgery, so it was only a matter of time before he was shifted to the 60-day IL. The left-hander will miss the entirety of this season and isn't likely to be back until midseason of the 2026 campaign.

Diamondbacks manager Torey Lovullo said Friday that Walston will undergo Tommy John surgery, Alex Weiner of ArizonaSports.com reports.

EDGE Analysis

It's not clear when Walston was injured, but he missed time last season while at Triple-A Reno with an elbow issue. Because he's a starter and it's a full UCL repair, the left-hander will probably be sidelined until around midseason of next year.

The Diamondbacks optioned Walston to Triple-A Reno on Thursday.

EDGE Analysis

Since rejoining the D-backs' bullpen Sept. 15, Walston has surrendered eight runs (five earned) over just 5.2 innings while striking out seven batters and walking one. He and Yilber Diaz will end up as Arizona's roster casualties following the activation of Ryne Nelson (shoulder) and promotion of Alek Thomas, and the 23-year-old Walston likely won't make it back to the majors during the final series of the season this weekend.

The Diamondbacks recalled Walston from Triple-A Reno on Sunday.

EDGE Analysis

The left-hander was activated from the injured list in mid-August after missing two months due to an elbow issue, but he was immediately sent to Triple-A. Walston has started in two of his three appearances with Arizona this season, but he's likely to work in a long-relief role this time around.

The Diamondbacks reinstated Walston (elbow) from the 15-day injured list Monday and optioned him to Triple-A Reno.

EDGE Analysis

With Eduardo Rodriguez and Merrill Kelly both recently returning from the IL, the Diamondbacks don't have an open spot on the rotation for Walston. For now, Walston will head down to Triple-A, but the 23-year-old southpaw should eventually make his way back to the big club, possibly as a multi-inning option out of the bullpen if the rotation isn't impacted by injury. Prior to landing on the IL on June 6 due to left elbow inflammation, Walston registered a 2.84 ERA and 1.42 WHIP across 12.2 innings in three major-league appearances (two starts).

Walston (elbow) struck out five and allowed two hits and no walks over 3.2 innings in a rehab start for Triple-A Reno on Sunday.

EDGE Analysis

According to Jesse Friedman of GoPHNX.com, manager Torey Lovullo said July 26 that the Diamondbacks were undecided on what Walston's role might look like upon the left-hander's return from the 15-day injured list, but Walston's usage Sunday implies that he'll be built back up as a starter. With Eduardo Rodriguez and Merrill Kelly both beating him back from the IL, the Diamondbacks don't have a rotation spot available for Walston at the moment, though the complexion of Arizona's pitching staff could change by the time Walston is ready for activation. Walston posted a 2.84 ERA and 11:9 K:BB across 12.2 innings in three outings (two starts) for Arizona before landing on the IL on June 6 with a left elbow strain.

Walston (elbow) threw live batting practice Friday, Jesse Friedman of GoPHNX.com reports.

EDGE Analysis

Walston touched 94 mph during the session, an encouraging sign considering he hovered between 91 and 92 mph during his three appearances this season. The 23-year-old southpaw is expected to be activated from the injured list sometime in August, but manager Torey Lovullo indicated Friday that the team was still determining whether he'll be an option for the big-league rotation down the stretch.

Walston (elbow) isn't expected to return from the 15-day injured list until sometime in August, Theo Mackie of The Arizona Republic reports.

EDGE Analysis

After turning in a 2.84 ERA, 1.42 WHIP and 11:9 K:BB in 12.2 innings through his first three big-league outings (two starts), Walston was placed on the 15-day injured list June 6. His injury was initially classified as left elbow inflammation, but the Diamondbacks have since listed him with a left elbow strain, according to MLB.com. While Walston has resumed throwing off flat ground from 60 to 100 feet, the Diamondbacks haven't yet indicated that he's been cleared for bullpen sessions, so he still looks to be several weeks away from being stretched back out for a starter's workload. All of Jordan Montgomery (knee), Eduardo Rodriguez (lat) and Merrill Kelly (shoulder) are further along in their throwing progressions and appear poised to beat Walston back from the injured list, so the 22-year-old southpaw will most likely be optioned to Triple-A Reno once he's activated.

Walston was placed on the 15-day injured list due to left elbow inflammation, Alex Weiner of ArizonaSports.com reports.

EDGE Analysis

Walston was called up to make his first MLB start May 27 and made an additional start Tuesday. He was not part of the decision in either start, but he gave up just two eared runs in 9.0 innings. However, he will be unable to make a third start soon with the apparent injury that came of Tuesday's game. The Diamondbacks selected Humberto Castellanos from Triple-A Reno in a corresponding move.

Walston did not factor into the decision in Tuesday's win over the Giants, allowing two runs on two hits and four walks while striking out two over 4.1 innings.

EDGE Analysis

Walston didn't have his best stuff, evidenced by his four walks, but was able to keep the Giants at bay after the Diamondbacks got out to a 3-0 lead. Walston had a full count on six of the first nine hitters he faced and needed 50 pitches to get through two scoreless frames. The Giants eventually got a run across in the fourth and another in the fifth after Kevin Ginkel was unable to strand one of the two runners he inherited. Walston now owns a 2.84 ERA, 1.42 WHIP and 11:9 K:BB over 12.2 innings. The 23-year-old figures to get at least another look in the rotation while Zac Gallen (hamstring) makes his way back from injury. Walston lines up to face the Padres on the road this weekend.