When you are short it's easier to controll the game because you will have better balance. Just look at players like Xavi, Iniesta, Thiago, Modric, Veratti, Seri, Cazorla, David Silva, Bernardo Silva, Coutinho, Isco. They are all short players. Imagine players like Rakitic and Gomes controlling the game? Loool, impossible because they are too tall with their long legs. If you have the technical abilities with strong mentality, then you have everything to become a world class CM. You don't have to be physically strong because your body will automatically grow every year.
Yes ofc you can be taller than 175.. players like Kroos, Pjanic, Koke, Jorginho, Kevin de Bruyne, Ozil, Eriksen, Fabregas, Vidal, Herrera, Yaya Toure, Fernandinho, James Rod and Kovasic are all taller than that. Even Aleña is taller than that, but he's only 180 like Kroos and Koke f.ex. I think it's disgrace to be tall like Raktic, Gomes and Pogba. Key to success as a CM is being short like Xavi and Iniesta, but 180CM is ofc acceptable. Tall players will never be a controlling CM because they don't have the ability to be that with their long legs. So Yes I hope La masia continue to produce short central midfielders. I refuse to believe that a 190CM tall player succeed in Barca as a central midfielder.
And when it comes to Adria, he has everything a CM needs to succeed in Barca. Just need to grow more, keep working and remain with strong mentality.