That's kind of a silly thing to say. I wasn't claiming that all players should be equal, but this is supposed to be a video game, not a university lab simulation. Some things need to be sacrificed for fun, and IMO this is one of them. Losing a game because my WR chose that particular 3rd down to have his ratings induced goof off play would intensely frustrating. Besides, Speed is easy to measure, heart is not.
Either A) you will be at the whims of a random number god when deciding whether this player is drifting or B) you'll have a personality guessing minigame where you try to boost them up. Neither sounds appealing. In Head Coach 09, they had a choice of whether to chew out a player after a bad play or console them. The choice you made (IME) seemed to be completely random. After Trent Edwards threw a ridiculous pick that ricocheted of the WR and a Defender, I chose to console him because, hey, it wasn't his fault. But he still took a penalty for it. There seemed to be no real relation to the situation or the players' actual personalities.