Rest vs rust argument

I know it's the beginning of the season but this game like the Falcon's playoff game shows that this team doesn't do well with rest. They haven't proven capable of having time off and showing up ready to play. As of right now the resting of players in the preseason appears to be a mistake.
Is the quick strike attack an Achilles heel of this defense or is it just too many new pieces and too little snaps played together???