Youth leagues

Can someone give a summary of how the youth league system works? I'm confused as to how Mitroglou can play in an official U21 match when he's 25 years old. I assumed that when players were making rehab appearances, the games that they participated didn't count. But the U21s just moved six points clear in the table thanks in part to two goals by Mitroglou.

 

You're allowed to play three overage field players and an over-age goalkeeper. I think the U21 league replaced the reserve league so they kind of have to do that so that older players coming back from injury have a place to get games. Or at least that is what makes sense to me.

 

Thanks Mo. I didn't realize that the reserve league is no longer. Is that a recent change?