Berge's time at United can be split in two before and after Man U at home last season. Before then he'd appeared in every game since joining (24 starts, 2 sub apps), after he's made 9 appearances in 45 league games and a third of those appearances have been as a sub. He wasn't a "knacker" when we signed him but he did have a freak injury and his recovery has been patchy.
Mousset, on the other hand, just needs constant care. It shouldn't be the club's responsibility but if he's not capable of looking after himself then we need to employ someone to do it for him.