Castano was left off the Marlins' 28-man roster for the team's NL Wild Card Series with the Cubs that begins Wednesday, Mark Feinsand of MLB.com reports.
Castano was the star of the Marlins' win over the Yankees in the regular-season finale, covering 6.1 shutout innings of long relief to capture his first big-league victory. The heavy workload he logged Sunday may have made the Marlins reluctant to include Castano in the bullpen for the three-game series, but since he's still a part of Miami's taxi squad, he would be eligible to rejoin the active roster later in the playoffs.