The idea is to search for a player with a profile similar to David, Bernardo is one option, but he plays better off the right. David wasn't a 25 goals per season player. It's the same tempo quote again. Pep would play Foden in midfield but he does not because he said you need to be able to control and switch tempo playing in the middle compared to playing on the wing. Grealish can do that, he is up there as the ball carrier in Premier league, gets goals, can pick a pass out.This, 100%!
What does Grealish bring to the team? Based on what I’ve seen, he is another upper echelon attacking midfielder of which we have many. His form against teams that press high is poor (for him), he can be prone to lose possession, he only contributes ~15 goals per season as the top attacking player at Villa and he is a proper shithouse with a massive ego and drink driving record.
To pay £100 million for someone that doesn’t generate 25+ goals per season seems foolish, especially given his character flaws. Furthermore, he is likely a squad player and won’t get into the starting XI on some days. Anything over £50-60 million seems like too much; he isn’t a clearly better choice than Bernardo, Gundo, KdB etc.
He is a very good player, and players like that don't come cheap these days, especially when big clubs try and pick them off their clubs. Whether the value is justified or not is always debatable, because let's be real, the market value does not reflect a player's quality in today's game. Maguire isn't a 90m centre back, but the rags got him anyway because they think he's important and can help them.