I think the problem is Ole is not a strategic coach, he's a man managment coach. He cant "afford" to upset any of the best players, he doesnt have the balls to take Rashford or Bruno out, he wont do a thing that compromises the atmosphere of the dressing room.
Greenwood was having a good game and Rashford had his worse game in a long long time, still he subs Greenwood.
He's the type of manager that puts the best players out, works on them being happy and hopes that enough to produce performances and results.