I was one of the people that said madden needed player tendencies/player styles/ability system like apf 2k8 does, and I still feel that way. The problem with madden 20's x factors is exactly what you mentioned, they are cheesy and unrealistic.
I realized this immediately when I was watching some random youtube clip of some guy breaking a bunch of highlight, once a year type long runs with Barkley(giants rb) to 'get in the zone'. The way it's set up in apf 2k8 is a lot more natural and realistic, and in the flow of the game.
But in madden 20, it's a poor implementation that only highlights the bad gameplay, and makes it even more unrealistic. I don't like the way ea went about this. Personally, I feel that if the player ratings translated into the on the field gameplay better then maybe a system like this wouldn't even be needed.