He says he burned out, etc etc. But look at this clip at 11:42 on the lead up to the Bisping fight. Because of his torn ACLs in both knees, GSP is walking like an old man. A champion has to be an active fighter. An active fighter has to defend his title 1-3 times per year. I don't think GSP is capable of fighting that often. I think he can scientifically plan out 1 camp to not aggravate his knees and then fight at 80% of his potential, which is still good enough to be a champion for 1 fight. GSP is probably physically unable to fight 95% of the time and the Bisping fight was once in a blue moon where his body was feeling OK. I think he's in the position that Dominic Cruz is in.