I disagree with this. Is it not the manager's responsibility to coach up the squad players, or to encourage them, or to give them a tactical platform that optimizes their pros and limits their cons?
Instead you have Ole saying he can't trust them. And it must be so incredibly frustrating to not be given a chance even when the starting 11 lads are clearly running on empty, or in a serious decline in form. We struggled for weeks during the bubble, yet the same 11 would play no matter what. Then often they would remain out there struggling, dead on their feet until late in the match, when substitutions would finally be made reluctantly.
How about creating an atmosphere of competition for places? What motivation does James have when he must know that Rashford is going to start and play if healthy, no matter how poor he performs, and no matter how long his run of poor form lasts. Same for Igalho, Fred, and McTominay. Pogba can look disinterested, and unfit, and be robbed of the ball 25 yards from our goal five times a game but we all know he will start the next match and play the full 90, no matter what. And similarly, what motivation does that give Rashford, Martial, Bruno etc? They aren't fighting for their places, they are secure that they are the special players that "can be trusted" so its not a big deal if they are poor, they know they will get a chance at redemption the next match.
The only exception to this is with LB. There actually isn't a sufficient LB other than Shaw, so he has to play every week. Instead we have multiple RBs that can "do a job" at LB and not embarrass themselves, but they aren't offering anything in creativity, possession, or width.
I'm not saying the second string players are actually hidden geniuses. I just don't think we are getting the most out of them.