Although my thought for this is not just a chemistry it's a chemistry. From the NFL, each trainer has an identity they exude in their team, a character trait and a design, why not include this? The main reason being trainers currently have very little importance in MUT. This may not be a big deal, but it seems to add customization that'll enhance drama for some, to a game mode. https://www.mmoexp.com/Nfl-20/Coins.html