Vitor still looks bigger than Machida. His technique is still there. Less muscle may translate to a better gas tank and more endurance. There are both positives and negatives facing Vitor right now. Calling the fight a wash in Chris' favor against a veteran like Vitor is ridiculous. It seems like every dude and their mommy is on the Weidman bandwagon these days. I foresee a bubble forming around this guy, much like the real estate bubble of 2008... And when it pops and Chris goes down, there will be a lot of tears to go around, just like 2008.
I still think Anderson Silva is the overall better fighter, but I also think Weidman is the real deal. I think Weidman has not the same intuitive knowledge understanding about fighting like Silva, but he follows the instructions of his coaches probably better than any active UFC fighter at the moment and he has shown some incredible timing and distance management. He is not flashy and won't use a variety of techniques like Silva, but he uses basic techniques close to perfection. I don't think his outings will pop like a bubble. He may lose the belt at some point, but unless he gets real confidence problems after a loss, I'm sure he will stay in the Top5 for a long time.
I think they can be linked, no doubt. I want to see evidence Vitor did show lack of confidence in the past as compared to his TRT phase. His body? Visible differences. His confidence? No way.
Testosterone has a huge effect on aggression. Aggression leads to tunnel vision and reduces fear. So yes, TRT has very likely also a significant influence on the confidence of its user.