It is her basic position that the "system worked" because the bureaucrats responded properly after the attack. That the attack was "foiled" by a bad detonator and some civilian passengers is proof, she claims, that her agency is doing everything right. That is just about the dumbest thing she could say, on the merits and politically. I would wager that not one percent of Americans think the system is "working" when terrorists successfully get bombs onto planes (and succeed in activating them).
Here's Goldberg's assessment of the role that Napolitano seems to be playing:
Napolitano has a habit of arguing that DHS is a first responder outfit. Its mission is to deal with "man-caused-disasters" afer they occur. It appears she really believes it.
Watch the video and see if you don't agree.