If you look at the breakdown of ages within successful squads in real life there are a few young guys under 22 , a few older guys over 29 with the majority in that mid section of 23-28. This is a recipe for your squad reaching its maximum potential which is known and acknowledged worldwide. Sure occasionally teams that dont fit into this formula are actually successful but the vast majority fit this formula.
It would be great for this game to follow something that is real.