[cdon2k]

here's some reasons why it happens and a possible fix:

Why it happens:
A majority of the time when in a cover 3 coverage, the FS who is over the slot drifting back into a blue zone does not change his coverage to react to the slot receiver moving into the area shallow of his zone assignment.

Other times, there is a quick cut animation that a lot of slot routes use that is unmatched because there is no defensive animation that compares to this quick cut in and up.

How to counter it:
When calling cover 3, flip the coverage (X button on 360 and then R trigger) so the the Saftey who is the yellow short zone is over the slot receiver. For a little while I was taking control of the Safety in the deep blue zone and cheating down to cover the slot, but that can get you beat over the top because of your absence in the deep zone area. The new locomotion system has also made it more difficult to cheat down and cover and then return back to your original assignment, so flipping is probably they way to go.