What does that even mean? I'm simply comparing their own performances this season and last. It's not about absolute level of performance, just meeting their own expectations as footballers.
If constantly changing team selection and formations was as big an issue as you imply, chances are they would play worse this season and last. Both Fellaini and Young have played as a wingback and fullback, looking decent in both positions. Fellaini's played in at least three different positions. All three of them have played about as well as we could expect them to play. They certainly haven't performed far below expectations, which is what Di Maria is doing.
Obviously, he is adjusting to a new team/league. So that's a good excuse. I'm not buying the excuse that he should be uniquely forgiven for under-performing because of inconsistent team selections and formations. Especially when he's played, at most, two games in an unfamiliar position.
It means looking at it without objectivity and pre-considered notions.
It's not really science Pogue. You know, a team can be playing really well and still lose because 1 player messed up or a team can lose and a player can play well. There are many different reasons for it. I'm pinpointing the tactics and personnel change as they are one of the least consistent aspects of the game. Not just within the season itself but also by looking at previous seasons. These are new tactics for the most part.
Just have a look for yourself. How many players are playing worse, how many are doing better, how many are performing about the same. Personally, I feel a lot more players are not playing as well.
You can compare him with Sánchez but the difference it that Arsenal have used the same tactics the whole season, tactics that Sánchez is used to. He's played with freedom to do what he does best in his favored position. None of this applies to Di Maria. He had never played as a midfielder in diamond before. Also, when he played in midfield he had, get this, midfielders playing with him. Shocking right. Playing with people in their best positions is the way to go.
No, I blame the manager for most it and I do it because of what he has said compared to what he has done. He said he plays entertaining football. He hasn't done that. He said he doesn't shoehorn players in the side but rather builds a formation around what he's got. Hasn't done that. He says he usually starts slow. Has done that. Great. Of all the things he has said, only his faults have come true. Also, from what I can gather from his interviews and player interviews, is that he kind of stifles creativity. The way the players play certainly doesn't disprove that.
He also said one thing, which I agree with, that players usually start of slow when they are new to a team or a league. That's definitely true. For every Sánchez and Costa there's an Evra and Drogba and more.
If he's below your expectations then that's your own fault.