Wouldn't boo him. It's a bit of a shame for him really, imagine he had hopes of stepping up a level (and not just more money). No way he's turned down top flight here or abroad for Sheffield United.
It's a training game. I very much doubt this would have happened unless our performance director thought it was a good idea to get players in optimal shape for the season.
Yamal is too. Although arguably so is Saka. We don't really have that quality on the other side though, probably something we need to solve to get more balance.