Wacha was removed from Wednesday's game against the Diamondbacks with right shoulder tightness, Derrick Goold of the St. Louis Post-Dispatch reports.
Prior to exiting, Wacha allowed two runs on four hits and two walks while striking out three batters across 1.2 innings. Mike Mayers entered the game for the right-hander, whose postseason availability is in jeopardy following this injury.