'Wanting CL Football' was always code for 'I want a pay rise'. United are one of the few clubs who can pay 100m transfer fees, 300k wages and 10m signing on fees. Players will see it as investing in a project but mainly they're getting dirty filthy rich.
So United effectively are grabbing Griezman and spending another 200m. The only plus side for us is that it shakes up their squad stability and kills one or 2 of their young players. I think Griezman is a fair bit overrated to, he's basically a Theo who can actually shoot with the laces but still plenty of limitations. Also it's not like United don't have a very good attack already, they can play:
So Martial, Mkhitaryan and Rashford all see their opportunities cut.
Mourinho is going to expect Griezman to play as a wingback at times presuming he's on the wing. At Atletico he played with more freedom as a secondary striker. He obviously won't do quite as well as a wingback with more defensive responsibility.