More injuries. But, really, we also have been getting players back. It's been a constant shuffling of the line-up, really all year. Someone mentioned that the Saints have not started the original 22 players Payton had etched in as his "first string." Not once, not even in the 4 pre-season games. All teams suffer injuries, that's true. But, hell! you also see it affecting other teams too. the NY Giants have had injury issues and look how they're doing. For the Bengals' game we were down to just 10 of those original 22 starters. Now, some have come back, but we've also lost a couple of those 10 since then!
BUT! it is also true that due to all the off-season, salary cap moves, the Saints were looking at a rather inexperienced and thin talent pool. If the Saints had stayed healthy (reasonably so) we might still have struggled to go 10-6. This 2014 team was gonna be Payton's weakest since he got here. The injuries have made it worse.