The Cardinals released Ferguson on Sunday, Derrick Goold of the St. Louis Post-Dispatch reports.
Ferguson was designated for assignment by St. Louis on Saturday, and he will hit the open market after going unclaimed off waivers. Acquired from the Reds on Aug. 3, Ferguson struggled to an 8.64 ERA and 2.28 WHIP with nine strikeouts over 8.1 innings in nine appearances with the Cardinals.