De Los Santos struck out one in a perfect inning in Tuesday's 8-3 win over the Royals.
Since he was recalled from Triple-A Columbus on May 9, he's allowed just one hit and no walks with nine strikeouts across 7.1 scoreless innings. The right-hander is still seeing mostly low-leverage work, but he's done well to post a 2.08 ERA, 0.69 WHIP and 18:5 K:BB across 13 innings this season. He's also picked up a hold in 12 appearances.