What is the weakness of Cover 3?

What is the weakness of Cover 3? The primary weaknesses in cover 3 are the seams (the area between the deep zones) and the flats (the area near the line of scrimmage on each side of the field.)

The primary weaknesses in cover 3 are the seams (the area between the deep zones) and the flats (the area near the line of scrimmage on each side of the field.)