Far too many of those - Oliva was great but..., I know Bostock had already left but ..., Castino, Koskie, Liriano*, Ortiz (for different reasons), Morneau, and now Mauer. Edit - One more to add - Scott Erickson was absolutely dominant for a little more than half of the 1991 season. He had a bad start, tweaked his elbow (not necessarily in that order), missed a start or two, and was never the same. Maybe it was smoke and mirrors, but I think it was more than that. * - Santana had one of the best 4-5 year runs in history, and for 2006(?), in the middle of that run, he was the 2nd-best starter on the team until Liriano hurt his UCL.