Silva has just never been the same since getting knocked out by Weidman and followed up by losing to him again and breaking his ankle in the rematch .... 1 win, 7 losses, and 1 no contest in the last seven years.
hindsight is 20/20 so it's easy to say he should have "hung it up" after the Weidman losses, but the man is a fighter and loves it. also probably got a piece of the PPV money so can't blame him.