Diehl, 23, spent the entire 2017 season with the Charleston RiverDogs of the South Atlantic League. The lefty out of Louisiana Tech struck out 101 batters over 85 1/3 innings in 28 games, earning a 9-3 record with a 3.16 ERA.
Diehl made five starts for the RiverDogs in 2017, all of them coming in the first half of the season. As a starter, he went 3-2 with a 5.16 ERA and 26 strikeouts. His real success came as a reliever where in 23 games he was 6-1 with a 2.44 ERA and 75 strikeouts in 62 2/3 innings pitched.