Cook, the team's opening day starter, was shut down for the year when he re-injured his left abdomen in a rehab start Saturday night. Rockies manager Clint Hurdle made the announcement Sunday before a 4-3 win at Arizona.
Cook had not pitched since Aug. 10, and he was placed on the 15-day disabled list on Aug. 20.
Cook was 8-7 with a 4.12 ERA. He was 3-1 with a 2.41 ERA after the All-Star break.
The 25-year-old Hirsh broke his right fibula when he was hit by a line drive off the bat of Milwaukee's J.J. Hardy on Aug. 7. Hirsh shook it off and pitched six innings to get the win. The next day, X-rays showed a fracture in the right fibula, the thin bone on the outside of his lower leg.
BREWERS: Despite a slide in the NL Central standings and loud grumbling from fans, Milwaukee principal owner Mark Attanasio gave manager Ned Yost a firm vote of confidence on Monday.
Speaking during the Brewers-Astros game at Miller Park, Attanasio expressed surprise at the amount of criticism Yost has received since the Brewers squandered their division lead last month.
Given that the Brewers haven't played meaningful games in September for years, Attanasio said he wondered why more people weren't asking him if he'll pick up the club option in Yost's contract for 2009.
YANKEES: Roger Clemens got banged up by the Seattle Mariners, and then left the clubhouse after the 7-1 loss on Monday to get an MRI exam on his right elbow.
The 45-year-old, who allowed five runs and eight hits in four innings to lose for the first time since late July, felt his elbow tighten up during the game, manager Joe Torre said.
"First three innings it was a manageable situation for him and then it started to tighten up," Torre said. "Hopefully it's just something that needs a little rest."
TWINS: Joe Mauer might be out for another week with his latest lower-body injury, a strained left hamstring.
Mauer and the Twins were worked up after both local newspapers published columns calling for Mauer to be moved from catcher to third base.
"Fill one big gaping hole at third base? Let's just make another gaping hole behind the plate? Tell me which one's more important," manager Ron Gardenhire said.
ROYALS: Activated outfielder Mark Teahen from the 15-day disabled list and recalled pitchers Kyle Davies and Leo Nunez from Triple-A Omaha before playing the Rangers.
The right-handed Davies, acquired from Atlanta on July 31 for reliever Octavio Dotel, was sent to the minors on Aug. 31 in order to clear space for Mike Sweeney.