Willis resumed his rehab assignment with the Mud Hens Monday night, allowing five runs on seven hits over 5 2/3 innings at Charlotte. Three of those runs and four hits came in Willis' sixth and final inning after the hurler gave up back-to-back solo homers in the second.
"[Mud Hens manager] Larry Parrish [and other club officials] were pretty pleased," Leyland said. "He really pitched well until the sixth. He ran out of gas a little bit."
Willis walked three batters, but one of those was intentional.
The 25-year-old left-hander has made just two starts for the Tigers because of a hyperextended right knee he suffered when he slipped off of the mound April 11 at Chicago. He also tossed 4 2/3 innings of two-run ball with no walks on May 2, but was brought back from rehab afterwards out of concern he had aggravated his knee injury.
Jason Beck is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.