Dennis Allen's defenses with the Raiders ranked 28, 29, and 32 in the league. I don't see it as very unlikely that Dennis Allen could post a bad defense if things go wrong, he has done so the majority of his seasons as a head coach. With the Saints, he benefitted from a culture led by Sean Payton and managed to assemble a strong veteran defensive core. As that core ages out and the culture of Sean Payton fades, nobody knows if the Saints defense will remain strong or not. Certainly throughout the league there is a long history of many respected defensive coordinators and defensive minded head coaches whose defenses have been very strong some years but also have had off years as well.