The change it is hard to believe and understand, but he probably got several procedures from face lift to eye surgery and facial implants on cheeks and chin.  The issue on his case is that these implants maybe permanent and the only solution for that would be to change them for smaller ones, which could end worst at the end. It could be that he got also work on his nose done (rhinoplasty) as a very vulnerable area for a wrestler.  Some people even think that he receive lips augmentation. 

All these is very hard to confirm if it is not Mickey himself who open up about it, but at least thanks to his last movie we can be sure that even if he doesn't look the same, he is still a great actor who can be confident with himself and stay away from more plastic surgery.