They need to modify chemistry in the next edition. Maybe it'll lead to more diverse teams, instead of everyone playing near enough the same players.
Also if a player uses a substitute in the first half then the team should drop to the chemistry it would have if they started. As a way round the chemistry sub BS.
Add a possible shirt number (1 chem)
If a player play 100 games for the club(full chem)
If the manager is same nationality and league then it's 2 chem not just 1