Mata played out wide for us a lot under AVB and was very effective. The fact that Jose wants him to play in a similar position this season only reinforces that.
I would hate this transfer to go through though: Mata is by far my favourite player and I really don't want to give United someone that potent.
I also have to say that it sounds like grade A bullshit. All the facts that we have point to it being a stupid deal. From Jose's comments on wanting an inverted winger (Willian is good with both his feet but unless I am mistaken he is stronger on his right foot and primarily plays on the left on in the middle), to the fact that Willian's agent is Kia Joorabchian (who of course would never, ever exploit a lingering interest Chelsea had in his client to squeeze Spurs for every penny) to the very idea of selling our best player of the last 2 years to our direct rival, none of it adds up.
This hotbed of speculation also seems to have arisen at the same point that all the papers wind up their THE BEGINNING OF THE END OF THE TRANSFER WINDOW GET HYPED specials and when there's very little else to talk about. If we really wanted to swap Mata for Rooney and get Willian in as a replacement, why have we waited until now? United have supposedly been interested in Mata for weeks, we have been after Rooney for longer and we've close connections with Willian for even longer. The only way it would make sense is if Moyes woke up this morning and suddenly decide that yeah, **** it, Jose can have Rooney.