Anderson would not become the player he is today if he moved to a Utd/Liverpool/City 2 years ago. Players need time to develop, especially those playing in positions such as CM and CB, away from the spotlight of massive clubs. Because in these positions mistakes are costly and if you are constantly scrutinized, you tend to start playing within yourself, afraid of making mistakes. You need to develop in an environment where the media scrutiny is less, that's why we see most players move to "mid table clubs" to develop in their early 20s before making the leap to a bigger one. Also, the risk of them getting dropped after making errors is less in these clubs than it would be in a Utd or City.
Of course, that is not to say no young players can thrive at big clubs, they absolutely can and a lot of it is to do with circumstances and player mentality. Ugarte would actually look a lot better playing for Forest than he does here because he would consistently get games and every mistake his wouldn't be amplified. That's why I never get this nonsense you keep hearing oh why didn't we get this and that player on the cheap? Because if he we did maybe they wouldn't develop into what they are today.
Sesko is actually a prime example of this. We have been trying to sign him since he was 17 but he didn't feel ready for the move until last year. And fair play to him because I am sure had he moved here at 17, he wouldn't be the player he is now.