Robertson faced six batters in a start on Tuesday night against the Texas Rangers, allowing two walks, two singles, a triple and a grand slam before Leyland removed him from the game. Texas went on to a 7-4 victory as Robertson lost for the fourth time in his last five starts.
Following the game, Robertson insisted he had no physical problems, but Leyland said the ball wasn't coming out of Robertson's hand the right way.
Robertson and Leyland had a 45-minute discussion prior to Wednesday night's game against the Rangers. Afterward, Leyland announced that Robertson would be placed on the disabled list and left-hander Andrew Miller will be called up from Double-A Erie to
replace Robertson for Sunday's start against the New York Mets.
Leyland refused to answer questions about the move, but he did say another pitcher would be called up from the minors on Thursday to be with the club until Miller's call-up on Sunday.
After the announcement that he was headed for the disabled list, Robertson wouldn't say his arm was hurting but admitted that his stuff hasn't been the same recently.
"Physically I don't know how you diagnose tired arm, but [the ball] isn't coming out the same," Robertson said. "It's probably the most beneficial decision for the team for them to make this move. I've said time and time again that I want to go out and do my part. Things happen like yesterday, you can't afford them in the position that we're in. You've got to battle through it and that's what I'm trying to do."
Robertson said some time off from throwing might be what he needs to end his slump.
"I'll probably have better answers in five or six days," he said. "We'll put something together with the trainers and go from there. I don't have any answers other than that. I want to do my part for this team and I know I'm capable of doing that."