I understand that perspective, we’ve got a lot of incredibly talented players.
Maybe hard to compare Grealish to a defender (apples & oranges innit) but if Mahrez or Ilkay were in that Villa side then I‘d imagine that they‘d be better rated as individuals virtue of the sharp contrast in ability between them and their team mates making them shine brightly and also the fact that they’d be central to almost everything happening.
And visa versa, if Grealish were in our side then he wouldn’t be quite so central to play so might not get quite such high ratings.
Grealish is still class though. He gets a slagging, from those less open to change, due to his haircut and tight shorts but I wouldn’t care if his hair do was a pink beehive and he wore a tutu instead of shorts because if he ever gets to wear our shirt then his ability as a footy player will be my only concern.