I've always felt Martial wanted to be a striker while Rashford wanted to be a Ronaldo type forward. As per Rooney and Ronaldo post-Ruud though, their positions were never fixed and I think that's what Ole is looking for over the next few years in attack. In Dan James and Greenwood he has 2 footed attackers while in Chong he has a left footed winger who can take it to the byline on the left or cut inside from the right, Giggs used to change with Ronaldo during games when we'd play 4-4-2.
I watched the game with a few people and someone pointed out to me early on that there was a lot of space down the wings for Chelsea as both Rashford and Lingard were coming central. In the second half I think Ole went away from the high press and we sat in a bit more, good in-game management.