This is why Diaco's defense isn't any better than Banker's. The main reason Banker's defense was terrible was because his "Quarters" coverage was effectively man-to-man most of the time. Short of having Pro Bowl-caliber corners, it's unrealistic to ask corners to have to play man-to-man defense everywhere on the field.
This is the play before their first TD - it should have been a TD but the QB overthrew an open receiver. Jackson, Lee and Kalu are locked up man-to-man on the three outside receivers. Williams is spying Freeman. Why we have to have a safety spying the RB when we already have seven guys in the box with only six blockers is unknown to man kind but that's what we were doing. Also, it is unknown why the three DBs would be looking at the QB if they are in man coverage.
With the entire field to work with it's tough to stay with a guy you're not watching.