The Phillies promoted Klassen from Single-A Clearwater to High-A Jersey Shore on Monday, Jonathan Mayo of MLB.com reports.
Klassen will be joined in Jersey Shore by one of the Phillies' top position prospects in shortstop Aidan Miller, who is also getting a promotion from Clearwater. A 22-year-old right-hander, Klassen had performed as one of the top pitchers in the Florida State League over the first two-plus months of the season, turning in a 0.71 ERA, 0.87 WHIP and 57:12 K:BB across 38 innings.