Diaz is a stationary target. A punching bag. Has been his entire career. That's why he's lost to so many average fighters, and always loses to above average strikers when their careers aren't 5 years behind them. Noons sliced his face from his skull like Hannibal Lecter. Condit made a fool of him almost on par with the way Edgar did Penn in their last outing. GSP dominated him in every aspect of the game, including conditioning, which is where he's supposed to be head and shoulders above the rest of the MMA world. He's been outboxed AND outgrappled by Sherk, Riggs, Parisyan, Sanchez, and GSP.
Condit is the only striker near Silva's level that he's ever fought, and Diaz had nothing to offer him except a few fruitless body shots over the course of 5 rounds. This is either going to be one long highlight reel for Silva's return, from start to finish, or it will serve to show he's not ready to come back. If he can't absolutely destroy Diaz then he should probably hang it up. That little fucking rubber ball that he bounces around during shadow boxing is a bigger challenge.