Bentancur and Gray worked well together today...as did Palhinha and Gray when he came on. The problem now is working out how to fit those in with Bergvall effectively, if Xavi is possibly going to secure the 10 spot.
Gray is an interesting player. His versatility is probably his strongest asset. I don't think he has settled into a defined role yet, and it may be that he never does as almost every academy seems to be obsessed with producing multi-purpose midfielders these days.
But it would be a shame if he doesn't, unlikely to be a regular starter at a high level as a jack of all trades.