Yeah and they'll work around that base 4-2-5 with several different personnel packages to account for certain situations. Heavy packages where they may have 3 true DT's on the LOS and 1 DE. Rabbit packages where the Jack linebacker walks down and puts his hand on the ground to rush from a DE spot (1LB, 1DE, 2 DT's)
Speed packages where they have 2 DE's lined up inside and 2 LB's rushing from DE spots with their hand on the ground.
But they'll always try to disguise where the extra guy is coming from from. The defense will constantly be moving and changing based on personnel.
You'll have the same sort of fluidity in terms of personnel out of 6 and 7 DB packages. They'll just find what works best from week to week depending on the opponent. It's the Saban/Belichick style of matching up. The assistant coaches will have to be on point in terms of substitutions to avoid stupid penalties like 12 men on the field, etc.
It's usually not as big of a deal in the NFL because offenses don't vary as much as they do in college. But I've seen it cost Alabama so many times. Causing Saban to go berserk on the sidelines. I can see Flores suffering the same agony a few times during the season.