The frustrating thing is that we've seen what he can do for us.
When he came on at Real Madrid he almost scored, twice, by running at the defence at pace and putting the ball across. This is one of his strengths and i don't understand why he doesn't do that more often.
Perhaps I can offer my thought here. Grealish is not a perfect player. He has strength and shortness. His first 3 steps are slow but once he carries the ball with speed, he is good. Also his shooting is good but not striker level good. Thus he was determined to be trained into a midfielder instead of forward in his youth.
What happened vs Real Madrid.
The first shot - Zinny delivered a good ball with perfect speed and weight to Grealish. This allows Grealish to run up to speed before the first touch. This avoids his slow first 3 steps problem. As u can see when he carried the ball the defenses could not stop him.
The 2nd shot - critically Gundo made a little overlap on the left when Grealish was in the shooting position. Madrid defenders had a moment of hesitation - thus it bought Grealish a slight space to shot. He pretended to shoot from right foot. The opposite rushed to block his right foot. But he moved the ball to his left foot and shot from there.
So the quality of Zinny's ball and the small overlap Gundo did unblock Grealish.
However back in PL or with opposite who studied him more, usually they won't leave that much space for him. Or be confused by Gundo's overlap (because Gundo is right footed as well). So chances like this are far more rare. He did not get this kind of support as well. For example last night when he made those silly shot if a teammate offered some small overlap it would be much easier for him to have a better angle. (I am not blaming anyone but just saying it seems overlapping is not part of our usual game plan).
It can be easily solved if Grealish pairs with an PL avg level left back who can deliver the ball with quality and can offer overlaps at times.
Otherwise it will be in all parties interest if City negotiates a deal with other team to make a transfer. Some other system may suit him better and City can buy a more suitable winger to pair with Cancelo.