We all watched the Heinecke show and gulped: "Brees will shred this defense." But the Washington game gives reasons to think the Bucs can take the Saints, and more specifically that Brady and the offense can play good enough to overcome the defense's shortcomings. First, the Saints defense is quite similar to WFT: WFT DVOA -19%, Saints -20.3%. The stats bear this out:
Pass Yds/G (WFT 191.8; NO 217.0)
Opposing QBR (WFT 81.4; NO 83.3)
Sacks (WFT 47; NO 45)
It stands to reason that Brady could have a similar performance against NO as he did against WFT, where only a few key drops kept him from 400+ yards and 40+ points. Washington was a good measuring stick for the Bucs offense.
In fact, the Bucs offense is outperforming the NO offense in DVOA by a decent margin: Bucs 26%, NO 7.5%. This stat is important because it adjusts for strength of opponent, removing the "Bucs only played creampuffs" argument, and weights recent games more, thus factoring in the Bucs late-season improvement.
So, the defense? DVOA: TB -7.2% to NO -20.3%. The DVOA spread between the offenses favors TB more than the spread between the defenses. Remember, the offense only needs to score more points than the defense gives up.
All this is to say, don't let the mid-season 38-3 humiliation color your view of this game. It should be close!