"In there for a bit" is a lot different than "healthy"
Staley played for the first half and then went down. Granted, that was enough to blow out the Pats, but hurt his hamstring in that game and essentially for the rest of the year after Bruschi's cheap shots. He barely played for the last half of the season after that first half.
Haggans was down (freak injury, I believe, but he didn't play against the Pats) and Bell was out. Bell's been gone basically the entire year, with the exception being some spot work filling in for Foote about midway through the season before he hurt his groin again. He's explosive when he gets a chance to play, however.
They've got a lot of players that are now healthier than they've been all year. I'm gonna break this game down in a few hours, and honestly, I'm positive that teams will underestimate them like you guys are after that piss poor game.