It's not an act, it's well documented that he has had knee and foot problems for pretty much his whole career, and for you to say otherwise is just low.
IIRC he didn't look good in the Soderling match.
Every loss is blamed on an injury when it's his physical style of play that is the root cause. If anything was wrong that day it was the unusual amount of short balls he left, not his movement.
Anyway this convo's about the top 55 all time and open era so best stick to it.