Nico hasn't developed his game enough to be a reliable sub or rotation option for the first team. Very good at making the safe pass but many youth players are. Currently, another one of the youths who you put with the main-team and they kind of fade into the background doing nothing because they haven't got the experience and ability that you get through seasons of play, and understanding different positions and tactics. Nico has only played pivot with Barca B who were by far the best team in Segunda B last season on paper. No use rushing players into the first-team when they aren't of the level yet. I think a loan would be great for him but for some reason we don't like to loan our Barca B players out without buy options.
And to make it clear, these players could develop to be really good like I've always said! But playing them with the first-team before they are ready doesn't help them, reduces their confidence and they don't get much game time. Not every sub 20 year old should be played with the main team.
He needs to lose weight. He looks more like a bouncer than a football player and it's clearly holding him back, he doesn't win many headers or use his size anyway and it is making him so inagile. He had this problem in Juvenil as well where he was very heavy, & Needs to be way more progressive to contribute in the first-team. Even in Barca B nothing he passed was vertical or in key positions, it's players close to him or behind him which is very necessary a lot of the time but as a midfielder you need to be able to create as well.