Only thorough GamePlan creation for CPU controlled teams can fix this issue. The problem is defensive playcalling. The CPU routinely comes out in base 3-4/4-3 man defense against 3-4 WR sets and this results in a slower LB covering a speedy/quick slot WR -or- a deep safety covering a slot WR and unable to close on a quick slant or drag route in time.
This is also the reason faster TE's are typically wide open when playing the CPU.