Given last season he was injured for most of the year like this year, the concern is he's going the Martial route with fitness. The other concern is that his "very good seasons" were basically the equivalent of playing Bruno's role for us, but to a lower level than Bruno. But we already have Bruno, who is our captain, so a bit pointless. The 3rd concern is team balance. It's a simple question of what midfield looks more balanced, even if you ignore Ten Hag's system and look at any future potential manager. What route do you want to go?
Option 1:
CF
LW Bruno RW
Mainoo or Casemiro
LW CF RW
Mount Bruno
Casemiro
For me, that 2nd option just is not working. And if we go a 4-3-3, then I'd rather still use Mainoo as the 8 ahead of Mount as he's a natural in that role, whereas Mount is just a different type of player. So either Mount is a stupidly expensive backup for Bruno, or we just get rid of one of the two. I'd rather keep the better player who is our captain and who is always fit.