I watched videos like this of Grealish before we bought him. Ive watched the whole thing again just now and still wonder the same (why we bought him). Regardless of position, there is nothing there (or from what we have seen of him in a city shirt) that makes him stand out in any way.....He is an average professional footballer. There is nothing in that video 'highlights' that any of our players current (and past) cannt do better. and more consistently.
KDB - better at everything, other than maybe (and I say maybe) in very tight spaces
Foden - better dribbler - can actually beat a man, beater goal scorer, better in tight spaces, better passer (especially in tight spaces)
Gundo - infinitely better at everything accept driving forward with the ball.
Alvarez - can play from the left or right, better goal scorer, better dribbler, good at running with the ball, can drop deep to link the play
Bernardo - better dribbler, better runner with the ball, better ball retention and better goal scorer and better progressive passer.
Sterling - better goal scorer in our team, better dribbler in that he at least (and succeeded at times) at beating a man, better assists. Fustrating player but at elast he was aggressive in the final third and scored goals.
Jesus - better at everything (ncluding goal scoring which for a striker he as poor at) - I include him cause he could play from the left as well and deeper if required to link play)
Zinchenko showed more in an advanced position in the odd time he played there for us than Grealish has!!!
The only other player to compare him to is Mahrez - and he is equally poor and ineffective in the majority of games as well.
All of them (baring Sterling) retain the ball just as well and would do even better if they played like Grealish....ie constantly slowing everything down, making sideways none aggressive passes or turning back towards his own goal and dribbling backwards and passing square or backwards....
David Silva - I also bet he was fouled just as much but didnt fall over and therefore didnt get the fouls - infact ive never seen a player kicked as much as David Silva). Id rather have David Silva at the age he is now than Grealish (and Silva would be as effecive no matter where you played him as would virtually all the others mentioned above.
If the argument is still that he is playing out of position then Im sorry, he shouldnt be in any position as all the other players are better than him at virtually everything.
Edit - I forgot Sane - better goal scorer, dribbler and progressive passer and better with assists...poor ball retention and positional play at times however.