Walden was placed on the 15-day disabled list Sunday with right biceps inflammation. The injury is tough break for Walden, who had emerged as the Cardinals' top setup ace after compiling a 0.87 ERA, 1.06 WHIP, and 12:4 K:BB ratio over his first 12 appearances, covering 10.1 innings. Walden's DL placement will be retroactive to April 29, allowing him to be activated as soon as May 15 if he recovers quickly. The Cardinals added Sam Tuivailala from Triple-A Memphis to restore some depth in the bullpen while Walden remains unavailable.