Grealish was absolutely a brand signing, Man City didn't need Grealish and I highly doubt he was at the top of Pep's list. He was purchased because he was arguably the biggest name in English football at the time and the owners of City saw marketing potential. That said he his a fantastic player and I do hope he doesn't waste his career. Just hope he's not another Micah Richards.
On a side note I don't think we can underestimate the impact Dean Smith had on Jack, I think he was key in getting him to focus on his game and he improved massively under Smith. He clearly needs strong management behind him and Pep is already showing that.