i noticed that also.
like a randomness to it.
But folks complain about it when it does happen at random then htye complain that it doesnt happen at random.
When i have a game where my RB who never fumbles,starts to fumble its okay with me because i know in real life players have off days. So i figure thats EA's way of making sure you have some off days. Same when i line up a kick perfectly but for some reason the field goal is missed.