Willian is a favourite of Mourinho. One of the best defensive wingers around..
Pedro is exceptional as a defensive minded winger too.
Also, he's not god damn pathetic in terms of end product like Willian is. I mean, seriously, Willian had 2 goals and 3 assists in 36 PL matches in a league winning season. That's beyond horrible, no matter how defensive minded you are. If Pedro can get even a fragment of the leash Willian has enjoyed under Mou, I have no doubt he'll outperform him in just about every aspect possible.
I really don't know whether to cheer for Pedro or hope he crashes and burns alongside his despicable manager. For what he's done in Barcelona, he deserves all the success in the world, but I really wish he'd picked another team to continue at.