Hill reworked his delivery during spring training in 2008 after some initial issues with his command but retained his spot in the rotation as the season began. He struggled to start the season, making five starts, and was 1–0 with a 4.12 ERA, striking out 15 but also walking 18. In his final start, against the St. Louis Cardinals on May 2, he walked four of the first six batters he faced and was removed in the first inning. On May 3, he was optioned back to Triple-A Iowa in order to get his control figured out.