Paul is known to exaggerate injuries to his knee. 
Exaggerate? Please.
The injury last time was far worse than the whole organization played it off to be. But, due to "modern medicine" (i.e. targeted steroids and heavy protective gear) they were able to minimize the effects.
The fact that he didn't have any surgery astounded me at the time. I wouldn't be at all surprised if he suffered structural damage, and this injury puts it over the top.
I was not sitting too far away, and this did not look good folks.
Edit: BTW, I suffered a similar injury playing ball (hyperextended left knee). I never had surgery, re-aggravated it several times, and haven't had the same hop on it since (in fact my left became way better because I can't jump/push off my left leg to finish right). Not saying it's the same thing, nor do I know how Pierce is going to be affected, but PP is definitely going to be crafty as time goes forward. Good thing he already is to begin with.