Arizona Diamondbacks Lefty to Have Tommy John Surgery

A tough blow for Blake Walston and the D-backs depth chart.

Arizona Diamondbacks' Blake Walston (48) pitches against the Texas Rangers at Surprise Stadium on Sunday, March 2, 2025. / Joe Rondone/The Republic / USA TODAY NETWORK via Imagn Images

Arizona Diamondbacks manager Torey Lovullo revealed a devastating health update for Blake Walston on Friday. The left-hander will undergo Tommy John surgery and is expected to miss about 14 months.

Walston last pitched in Las Vegas on March 9, and reported soreness after the game. Upon returning to Phoenix, he had imaging and second opinions, and it was decided he would undergo the procedure.

The 23 year old was drafted by the Diamondbacks in the first round, 26th overall in 2019. He pitched in every level of the organization's minor leagues, and made his MLB debut in 2024. Walston made two starts and five relief appearances, posting a 4.42 ERA in 18.1 innings.

In 94 minor league games, Walston had a 27-16 record with a 4.43 ERA. The largest chunks of his 445 minor league innings came in the extreme hitter-friendly environments of Amarillo in the Texas League and Reno in the Pacific Coast League.

The always affable and humorous Walston had some great stories to tell upon his call up last year. That outward demeanor off the field belies the competitor on the field. Not the hardest thrower, Walston is one to never give in on the mound, and always made the most out of the stuff he brought that day.

While he was not slated to be part of the Major League rotation, he was going to be part of the depth, ready to go at a moment's notice from the Reno rotation. That depth is now thinned out a little bit.

Stay tuned to Arizona Diamondbacks On SI for further updates on this developing story.

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