Alex Cobb back on the mound for Rays Rays starter Alex Cobb delivers a ptch against the Mariners in the third inning Thursday at Tropicana Field. James Borchuck / McClatchy-Tribune / August 15, 2013 August 15, 2013, 7:07 p.m. The Tampa Bay Rays reinstated right-hander Alex Cobb from the 60-day disabled list to make his first major league start since being hit in the head by a batted ball two months ago. Cobb, struck on the right ear June 15 by a liner hit by Kansas City's Eric Hosmer, pitched Thursday night against Seattle. To make room on the roster, Tampa Bay designated infielder Ryan Roberts for assignment. The Rays are scheduled to face Toronto left-hander J.A. Happ, who was hit in the head by Desmond Jennings' drive on May 7, on Saturday night. It will be Happ's first game at Tropicana Field since being injured and third start overall since returning from the disabled list. Philadelphia Phillies ace Roy Halladay pitched six innings in his first rehabilitation start since being sidelined by a shoulder injury. Halladay gave up three runs and six hits in his outing for the Gulf Coast League Phillies against Pittsburgh minor leaguers. The 36-year-old right-hander struck out four and walked three. ... The St. Louis Cardinals activated All-Star catcher Yadier Molina from the 15-day disabled list after he was sidelined by a right knee sprain. He was 0 for 5 in a victory over the Pirates. ... Milwaukee Brewers second baseman Rickie Weeks had surgery Thursday to repair his torn left hamstring. Weeks hurt his leg on Aug. 7 when he stumbled over his bat and fell while trying to beat out a grounder in the eighth inning of Milwaukee's 6-1 victory over the Giants in San Francisco.