First of all: great discussion, mate!
The thing about shockers is that we remember them much more vividly than the good things. If a goalie makes ten saves, they are quickly forgotten if he makes one mistakes. The same goes for a defender, albeit the other way around for strikers and wingers - funny, innit?
Injury was clearly a contributing factor - remember when he was thoroughly outpaced by Lennon (which most would be), you could see him almost limping as he was running - same happened when he was skinned by god damn Mackie! No wonder he struggled getting back in defense. He was clearly instructed to contribute in attack, but because of his injuries or whatnot, he seemed to struggle to get back, that and the fact that he played too much coupled with him not getting younger.
Now he is rested a bit more, looks fitter and runs like a normal person, not one of those zombies that are so popular on the big screen.
I don't see it as a coincidence if he is rid of his injuries - that would explain a sudden return to form, again coupled with him being rested a bit more. He played fifty matches in three (four?) seasons in a row - that's too much!
Here I think you are spot on. We had a world class defense with Rio, Vidic and Evra (always felt our right back situation was a bit more unstable). Vidic covered a lot for Evra, but Evra, with his blistering pace, covered for Vidic and his lack of pace. They worked really well together.
I also agree that Evra defends much better now. Could be because he is less complacent, but could also be because he has regained fitness and pace - against Chelsea he outpaced Ramirez - not many players do that, and last years Evra wouldn't have stood a chance.
Indeed - we have a very strong squad, unlucky with unjuries for sure, but hopefully the defense will sort itself out now. Looked good against Arsenal except for that last moronic goal where everyone dozed off.