The big difference between Garnacho and Sancho is that the former has looked world class playing the premier league, the latter has only managed that playing in Germany.
We just need to get him back to the player he was before Amorim/Ratcliffe decided they wanted him out. Under Ten Hag he was 1 g/a in 3, if he replicates that he'll be fine, if he can take another step forward he'll be a bargain.
His record since then isn't great but Amorim had no idea how to handle most of the attacking players they had then Maresca started to get a bit of form out of him but once he left that dropped off again.
For all his cockiness I think he's a player that needs a bit of support from his coach to make him feel wanted in the team, the more i look at both the highlights and his stats the more he looks like a player who could really push on under Emery. There's no guarantees but I can see why we've gone for him.