No doubt GSP had been using resources which the rest of the MMA world do to recovery from injury. Something we can’t discuss on here.
If you are interested from recovery from ACL injury your better off seeing your local physio or doing a search on you tube.
GSP would have to be the most over rated athletes going around, there’s a lot of hype with UFC fighters.
Just being objective, I was watching GSP power snatch ( 40kg) bench (90kg), jump squat ( 80kg) and these lifts weren’t explosive or powerful.
If you are interested in strength and conditioning for MMA, I would recommend searching for Randy Couture training. His training is specific for MMA and low risk for injury.