We had the same young players playing last season and Fernandes playing higher has nothing to do with them, that's a very special stretch to put it on the young offensive players. The reality is that your point made no sense Ole changed a system that he has used for almot two seasons to accomodate the certain players, if we follow your logic these players should have adapted their game and Ole shouldn't have changed the system.
The way you put one would think that the only difference between last season and this one is that Ronaldo and Varane have been added to the starting eleven. Today Ole effectively adapted his 2 years old system to accomodate mainly Ronaldo and allow him to start next to Cavani instead of playing wide, he then added a CB in order to free the fullback since he decided to get rid of one of the wide players in order to accomodate Ronaldo.
In other words Ole adapted the system to the players that he wanted to start, these players didn't adapt to the system Ole originally used. That's a fact and not really debateable.
I don't agree that he adapted his system to the players he wanted to play. I think he adapted his system to be more defensively sound and played the players that best suited the tactic. The aim today was a clean sheet, that was clear. He then went for the most experienced attacking players who could make the most of very little expected chances.
While I don't put all the blame on the young offensive players, I notice the defensive part of their game has dropped a lot more since last season. Why? Not sure. There maybe many reasons. But hey, if they can adapt to the 3-5-2, by all means give them some chances ahead of the oldies when they need to be rested. But if they can't adapt, well, what I'm saying is tough luck for now.
Maybe we can get another coach in the end of the season that can help them, or maybe we have to sell them if the 3-5-2 works so unbelievably well for Ole that he wins so many matches and stays in the job.