Since Ole takes charge Man Utd, Mata has only played 5 games out of 9, 4 games not even played for any minute.
0 mins vs Cardiff
81 mins vs Huddersfield
0 mins vs Bournemouth
63 mins vs Newcastle (substituted by Lukaku who score for his first touch)
62 mins vs Reading (score a penalty)
0 mins vs Tottenham
15 mins vs Brighton
0 mins vs Arsenal
90 mins vs Burnley
Quoted from Gary Neville's words a few weeks ago, he said
"Looking at what Ole Gunnar Solskjaer has done, he’s left out Lukaku, he’s left out Mata most of the time, it’s not a reflection of those two players but they do slow down attacks. They can’t move from one box to another quickly.
"They can potentially add things from the bench but they can’t play at this pace, they can’t make the movements of Martial, Lingard, Rashford, Pogba.
“There were always players in the team that could run.
“It’s the basis of every team. You look at Manchester City with Sterling and Sane or Liverpool with Salah and Firmino, every team has to have those players and with the likes of Mata and Lukaku and Fellaini in the team, it was too slow.
The matches vs Newcastle, Burnley prove that Gary Neville was right. Also you can see both Mourinho and Ole or Mike Phelan don't trust Mata to play big matches (0 mins vs Tottenham, Arsenal recently), because of his lack of pace and physical ability. Sometimes he can't handle the high pressing from weak teams as well (vs Brighton).
From tactical point of view, Mata 's best position is pure number 10. However modern football has charged. Defenders and goalkeepers are required to pass the ball, strikers not only scoring goals, but also need to know how to link up team plays. Pure number 10 starts to be eliminated nowadays. You can see Ozil from Arsenal, and James Rodriguez from Bayern, they both struggle under their managers of either playing number 10 or right wing.
People may say, Mata can be rotated with Lingard, however when your PLAN A players are injured, let's say one month, then your rotated players may start for first line-up for 4-5 matches, which may already affected the title challenge. Today vs Burnley is a good example, you can see there is a huge difference of performance starting Mata and Lukaku compared to the last few matches. You have never seen Guardiola and Klopp keep a big guy, or a slow player as their attacking PLAN B option. They sold Bony, Benteke, and keep players with pace and individual ability, because they know even their PLAN A players are injured, the rotated players will not affect their main philosophy too much, not like us, whenever we rotated players, our playing style is completely changed.
From financial point of view, his salary is 140k per week, which is the 5th high of the team, just behind Sanchez, Pogba, De Gea and Lukaku. So is it worth for a player with that little game time? We are Man Utd, i think we should keep a player based on his quality, but not because he is a nice guy. If we still keep Mata, which cannot offer him to play at his best position, cannot play him for the big matches, or even cannot play him against physical and high pressing teams, so what is the point of still keeping him? I can only see the gap between Man City, Liverpool and us will become larger and larger. They keep buying paceful, skillful wingers who can dribble the ball, and we keep our right wing empty.
I think we should offload Mata for free at the end of season, buying a proper RW, or giving chance for Greenwood and Chong, which apparently have more future than him.