The Diamondbacks are calling up their top prospect in their minor league system.

But that means they’re dumping one of their former highly regarded farmhands.

Arizona called up outfielder Ryan Waldschmidt from Triple-A, and to make room for their No. 1 prospect on MLB Pipeline, designated fellow outfielder Alek Thomas for assignment on Friday ahead of a matchup with the Mets.

Less than two years after he was taken with the No. 31 pick in the 2024 MLB Draft, Waldschmidt reached the top level of the minor leagues and has thrived.

He has a .289/.400/.477 slash line with 15 extra-base hits in 128 at-bats with Triple-A Reno. It follows a sterling 2025 season in which Waldschmidt hit 18 home runs with 78 RBIs and a .892 with in High-A and Double-A. His year-end performance got him a Double-A All-Star nod from Baseball America.

Thomas, meanwhile, has hit .181 with two homers across 94 at-bats this season. After back-to-back hitless games, he was 1-for-9 with four strikeouts in May.

The DFA is a surprising fall for Thomas, who was Arizona’s top-ranked prospect ahead of the 2022 season and was twice a Futures Game selection (2019, 2021).

And while he’s provided solid outfield defense (two outs above average this season) and speed on the bases, his bat has never translated to the big league level with a career .634 OPS.

Waldschmidt is not in the starting lineup for Friday’s game against the Mets.