Rockies lose ace pitcher to DL

Aaron Cook was placed on the 15-day disabled list Saturday with a right shoulder strain, a potential blow to the Colorado Rockies’ playoff hopes.

An All-Star last season, Cook is 10-6 with a 4.47 ERA in 25 starts. To replace him on the roster, Colorado purchased the contract of right-handed reliever Matt Herges from Triple-A Colorado Springs.

The Rockies began the day leading the NL wild card race by one game over San Francisco.

Cook was hurt during Friday night’s 6-3 loss to the Giants. Rockies manager Jim Tracy said Cook felt something in his shoulder during a four-pitch walk to Nate Schierholtz to start the fourth inning. Cook motioned to the dugout after the walk and was taken out after being looked at by trainer Keith Dugger.

Tracy said Cook will have an MRI on Monday and the early signs are encouraging that it won’t be a serious injury.

The Rockies signed Herges on July 17, eight days after he was released by Cleveland, where he was 2-1 with a 3.55 ERA in 21 appearances.

Short hops

Tim Wakefield will replace struggling Brad Penny in the Red Sox rotation. Wakefield (11-3) last pitched for Boston on July 8 and made his second rehab start Friday night since going on the disabled list July 21 with a strained lower back, left hamstring and left calf. … Reds manager Dusty Baker says third baseman Scott Rolen will be activated off the 15-day disabled list and start today against Pittsburgh. Rolen sustained a concussion when he was hit in the head by a pitch Aug. 2. … The Cardinals placed right-handed pitcher Kyle Lohse on the 15-day disabled list with a strained left groin. … Pirates shortstop Ronny Cedeño will be out until at least Tuesday with a slight fracture in his right pinky finger. Cedeño is hitting .261 with four homers and 12 RBI in 19 starts since being acquired in a July 29 trade with Seattle. … Former big league closer Armando Benitez and the Astros have agreed to a minor league contract. Benitez, 26, a major league All-Star in 2003 and 2004, was pitching for the Newark Bears in the independent Atlantic League. He was 1-0 with 16 saves.