Aren't the performance ratings a simplified version of what you're suggesting? I've had a ML for 2 seasons who's been getting 7-6 ratings. This isn't acceptable to me so I just bought a replacement with a 6 point advantage who has been getting 4-6 ratings. Clearly thing's aren't working out for the new guy. Not sure why, but I don't see how I need any more information to determine if a guy fits my scheme or not.