My approach is they care more about fumbling the ball at a lower value, so they use the two arm cover animation more often, and play a bit more direct. With a higher fumble value, the carrier tends to juke/spin more because technically there's a lesser percentage of them fumbling.
This is how I've approached it in the past, with the exception of the M18 issue that had the CPU RB running in mud.
I still think the directness is solved in the patch update, but also with the user's RBL being at 40.