That's excellent to hear that you showed them. I'm not even specifically referring to fatigue though, I'm talking about how a team can make a big signing in MM on the transfer market and not even put the guy into their lineup despite him being superior player than who they already have at the position.
I don't think a lot of us are necessarily clamoring for a complete overhaul of MM mode, it would just be nice if the cpu altered their lineup, and even nicer if fatigue was better implemented. But I would certainly not be unhappy with just the first thing I mentioned.