Leiter struggled during his return to the Marlins. He walked more batters than usual (60 in 80 innings, in addition to 88 hits). In 17 appearances (16 starts), he had a 3–7 record and a 6.64 ERA, and he took much criticism for the Marlins' first-half struggles in 2005 (they were 7 games behind the surprising Washington Nationals at the All-Star break). He was demoted to the bullpen in late June, but he returned to the rotation after an injury to Josh Beckett. On July 10, when the Marlins played their last game before the three-day All-Star break, he gave up six runs in three-plus innings.