Robertson, on the disabled list since late June for surgery to remove tissue masses from his left elbow, scattered three hits. He needed 43 pitches (including 26 strikes) to complete his outing, slightly lower than his rehab schedule would suggest for his pitch count.
Reports from the Tigers suggested Robertson hit 89-90 mph on his fastball, according to radar guns. That, too, would be an uptick, suggesting that Robertson is getting a freer motion in his arm with his elbow unrestricted.
Another rehabbing Tigers pitcher, Jeremy Bonderman, followed Robertson with an inning of relief, allowing a Wes Bankston solo homer as his only damage. He needed just nine pitches to retire the side, including a strikeout.
Robertson has allowed three earned runs over 7 1/3 innings in three rehab starts. Bonderman, limited to only one outing for Detroit this year due to right shoulder soreness, has given up seven runs on 13 hits over six innings in five rehab appearances. He'll continue to work out of the Mud Hens' bullpen, while Robertson is slated to pitch again later this week.
Jason Beck is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.