DENVER -- A Rockies bullpen that has shown significant improvement from last season will be without one of its key contributors, as the club placed left-hander Mike Dunn on the 10-day disabled list Wednesday with back spasms.
Right-hander Chad Qualls, who began the year on the disabled list with forearm tightness in his pitching arm, was activated to replace Dunn on the active roster.
Dunn most recently pitched Saturday against the Giants, making the DL move retroactive to Sunday. He signed a three-year, $19 million contract in December as a key cog in general manager Jeff Bridich's aggressive offseason, and the left-hander made an immediate impact on a bullpen that posted an MLB-worst 5.