From Mike Triplett: The Saints (4-5) are on pace to allow the highest opponents' passer rating of all-time (112.0), according to the Elias Sports Bureau. The current record of 110.9 was set by the 0-16 Detroit Lions in 2008. When asked about that dubious distinction, several Saints players had trouble deciding whether they believe it sounds accurate. The general consensus was they aren't really that bad, but they've been too inconsistent and have allowed way too many big plays.
Saints' pass defense historically bad; 'bonehead' plays don't help - NFL Nation - ESPN
An inconsistent Saints defense is on track to have one of the worst pass defenses ever -- due in large part to giving up too many big plays.