Diamondbacks call up top prospect Ryan Waldschmidt, DFA Alek Thomas

Ryan Waldschmidt forced Arizona’s hand in Reno, then gave the Diamondbacks the cleanest possible first answer in the majors. The 23-year-old arrived from Triple-A with a .289/.400/.477 line, three homers, six steals, 22 RBIs and 19 walks in 34 games, then singled in his first big league at-bat during a pinch-hit appearance against the Mets at Chase Field.

That promotion came with a corresponding move that sent Alek Thomas off the roster. Arizona had lost 12 of 16 and entered the weekend at 17-20, with an offense tied for third-lowest in the majors in home runs and on-base percentage through play Thursday. With Lourdes Gurriel Jr. still working back from the torn right ACL he suffered in September 2025 and Jordan Lawlar sidelined after fracturing his right wrist in early April, the Diamondbacks needed a bat that could help immediately, not later.

Waldschmidt’s case started with the quality of the strike-zone work. He reached base at a .400 clip in Reno, and the walks mattered as much as the power. He had already built a reputation for that profile after hitting .289/.419/.473 with 18 homers and 29 steals over 134 games in 2025 between High-A Hillsboro and Double-A Amarillo, while drawing 96 walks across the minors. Arizona saw that patience translate into Triple-A production fast, including a hot start in Reno earlier in April and his first Triple-A homer last month.

The Diamondbacks also knew exactly who they were promoting. Waldschmidt was the No. 31 overall pick in the 2024 MLB Draft as a Prospect Promotion Incentive selection tied to Corbin Carroll’s 2023 National League Rookie of the Year season. MLB Pipeline ranked him No. 49 overall, and Arizona had been close enough to the big-league roster in spring training that the idea of a midseason debut never felt far-fetched.

For the debut watch list, the easiest skills to trust are the ones that already drove the call-up: the walks, the contact quality, and the willingness to take a pitch deep into counts. Waldschmidt is a right-handed hitter listed at 6-foot-0 and 205 pounds, and his first test is whether his bat-to-ball skill and discipline hold against major league velocity. If they do, Arizona may have found the kind of outfield answer it was missing while Thomas, 26, faded to a .181 average with two homers in 100 plate appearances and a .230 career mark. Thomas still leaves behind a major October moment, including four playoff homers in 2023 and the tying two-run shot in NLCS Game 4, but Waldschmidt’s rise showed how quickly Triple-A impact can become a big-league decision.