I havent said I "wanted him sold", and yes, I would sell Rooney as well because I dont think he is of the calibre to be a #1 striker at an elite club any more, but that is for a different thread.
As I said, I think our best football this season came when we played 4-3-3 with a backward facing triangle (ie a DM and 2 CMs). Herrera and Fellaini worked very well as the CMs in that system, with license to get forwards frequently and join the attack, whilst Carrick did his thing behind them. I cant see Mata fitting into a central position unless we significantly change our system therefore.
Out wide, I just dont rate him as a wide player that highly. In the system described above, in my opinion you want a pair of inside-forward style wingers. The likes of Robben, Bale, Ronaldo, Depay and Nani. Especially if we are using a forward like Rooney who has a tendency to drop a little deeper anyway, you want the wide men to be direct players who can pick up the ball and run with it outside or inside, and that is clearly not Mata's game.
There has been talk from some (including
@NL Max) that we will likely be playing more of a 4-2-3-1 next season, as LVGs preferred system is using a forward facing triangle in midfield. I am not convinced that that will suit us better than what we did this season. I dont think Herrera's best role is as a deep lying midfielder (which he would be in the proposed system), and I also think that going into next season with potential changes to an already inexperienced back 5, we need to have a figure like Carrick who can screen the defence - which you do not typically get in the proposed system.
I realise that LVG has previously used that version of a 4-3-3, but he has also stated that he is not so stubborn that he is above changing and adapting it when required - we saw that with the 3-5-2 (although it didnt work out).
So, my stance is unchanged. Mata is a good footballer and one of the most likeable players in the game. For these reasons it is understandable that he is a fan favourite, however he is not indispensable to the club. And if (and yes, it is an if) Di Maria gets back to form and/or Nani/Young remain and play well, then I dont see a place for Mata in the starting XI. I agree with
@Cina that there are plenty of players in the team who are more important than Mata.