How is it realistic that a player is somehow worse just because he's in a system that doesn't fit him? He's not worse, he just doesn't fit. What you're asking for is UNrealistic and redundant.
If I take over San Francisco and switch to a power run scheme, Jarrick McKinnon isn't gonna suddenly be a worse back... but he's going to perform worse because I'm running him on ISO all the time. That IS realistic. Having him suddenly forget how to juke is not. Dez Bryant isn't gonna forget how to run a dig if he signs with a team that doesn't run many digs, he's just not going to be used to his greatest potential if he isn't permitted to do what he does best.
What you're asking for is playbook knowledge, which I'd love to see but that would be its own feature independent of this one.