Flip should make a statement in the next game, to show everybody that his post-game rant was serious. He should bench the "Big" 3 and make it clear that if you want on the court, you'll have to earn it by playing defense.
His lineup should look something like this:
C - Haywood
PF - Oberto
SF - McGuire
SG - Young
PG - Foye
If Young starts missing his assignments, then he should be benched, McGuire should be slid over to SG, and Blatche should be brought in to play SF. If that doesn't work, then Flip should keep tinkering until he gets a lineup that is fully committed to defending. The message should be loud and clear.