Despite the millions of dollars invested into the new baggage handling system, it is prone to failure during periods of high volume. From what I understand, one of the main issues isn't the system itself, but rather TSA's inability (or unwillingness?) to staff enough baggage screeners for the amount of bags going through the system, which causes backups.
I can't believe it's already been a year since this happened:
http://www.ibtimes.com/american-airl...-issue-1823612