They hadnt given up a TD yet either - that stat means nothing IMO.
I think it means something... but I suppose they haven't played anyone maybe? (don't know sched). ALTHOUGH, that doesn't mean that they can't/won't give up a TD in the fourth. Just means they're defense is gonna stay stingy like it has all game. Well, I saw one series I didn't know what they were doing... probably cover 2 that didn't work.