Storey, 26, will be making his major league debut after five seasons in the minors. Acquired by trade from Oakland last season, he's put up a 7-4 record with a 3.05 ERA, 10.0 K/9, and 1.9 BB/9 in 65 innings primarily of relief work (2 starts in 38 games).
If my count is correct, this move puts Houston's 40-man roster back at a full 40.