Petit filled a variety of roles for the D-backs in his three seasons with the club, appearing in 56 games, including 35 as a starter. Over that span he was 9-19 with a 5.05 ERA and seemed to be a poor fit as a fly-ball pitcher in Chase Field, where the ball carries extremely well.
Slaten made the big league roster out of Spring Training in 2007 and had a 2.72 ERA in 61 games for the National League West champions. However, the lefty had trouble replicating that success in 2008, and he appeared in just 11 games in the Major Leagues in 2009, spending most of the year with Triple-A Reno.
In a pair of additional roster moves, the team removed outfielders Trent Oeltjen and Alex Romero from the 40-man roster and outrighted them to Reno.
Romero could elect to become a free agent rather than accepting the assignment.
The moves leave the D-backs with 35 men on their 40-man roster.
Steve Gilbert is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.