I'm a long time player and know how the concerns work but in one of my game worlds Aguero has gone up in concern level 3 times in what seems a fairly short space of time i.e weeks. He's made 32 starts and one sub appearance and still went up to level 3. Sanchez just got a level 1 concern with 30 starts and 2 sub appearances and that seems a little harsh. Kompany also got a concern with 32/1 start/sub appearances too.
I had a concern review in my game world today and also one 8 days ago.... usually I manager concerns really well but in one season for a player to go from no concern to level