The following is a message from UFC fighter and TUF veteran Rory Singer from The Underground Forum:
Forrest has had a majorly damaged shoulder for quite a long while. The injuries to his shoulder even before his fight with Shogun were exhaustive. You have never heard of it because Forrest never mentions his injuries, whether he has won or lost, after his fights. This surgery was a long time in coming. Everyone felt it was in his best interest to have the surgery now before fighting another top tier fighter. He basically fought Shogun with one arm. Trust me, Forrest wanted to fight Silva in December but that was not to be.
Thanks to MMANews.com Forum member Justin Bullock for sending in that find.