Dash riprock
Midfield
Im just going on general physiology , he was playing regularly for the last 2 years so there seemed to be no inherent problem .How on earth do you know that Mvilla not playing has extended his career? For all we know he may not have played because he cant play more than three games in a row. We have no idea.
A lot can be done on getting your body right when you can do stuff designed to restore it not max it out in competition.
That restoration will last so long under test ( barring injury ) hence the extra year .
I mean; dont " know" but i doubt its done his body any harm at 33. As i say that age is still just about prime really or not much over anyway .