Pereira was actually decent when he was being played at #10 or right wing last season. Not great of course, but he was comfortably outperforming Lingard and Mata in those roles at the time. It was noticeable that we looked better to the eye and were getting significantly better results with him than the other two. From memory we were averaging 2 points per game when he played in those roles compared to 1 point per game when he either didn't play or was in a deeper central midfield role. Obviously it was only over half a season so it was a fairly small sample size, but it was enough to be noticed.
Pereira's dreadful performances at central midfield seem to make people forget his better performances earlier in the season. He obviously isn't good enough, but I think some of the criticism he gets is unfair. I'll remember him fondly for those few months.
I do agree though that we should have tried to give Gomes a few more starts. He only got two starts in a central position last season and he was arguably our best player in both. The rest of his games he was played on the left which he doesn't really have the attributes for, and even if he had done well he obviously wouldn't get games ahead of Rashford. With Mata and Lingard both in the worst form of their careers I would have liked to have seen Gomes get a couple more opportunities. Otherwise though, I don't really have any issues with the treatment of youth players under Ole. He's done well and players have got chances when they should.