The bulk of Bills’ roster has been decided for some time. It’s the final 5-8 spots that remain up in the air as the team prepares for final cuts.

“About 80, 85 percent of it is done,” coach Chan Gailey recently said. “So you’re talking about the last 15 percent of your football team.”

As is the case every year, special teams will play a major role in the final spots on the roster. K John Potter may have earned himself a spot with his 100-percent success rate with touchbacks on kickoffs this preseason -- in this final prediction, he goes from out to in. LB Scott McKillop, another potential special-teams ace, makes way for Potter -- though he, too, could help on special teams.

QB -- In: (3) Ryan Fitzpatrick, Tarvaris Jackson, Brad Smith. Out: Tyler Thigpen. Analysis: The Bills didn’t trade for Jackson just to cut him a few days later. The struggles of Vince Young and Thigpen forced the Bills to re-examine their depth at QB -- Young has since been released, and it would take an eye-opening performance from Thigpen on Thursday to make the Bills even think about reconsidering. Thigpen is expected to play most of the game against the Lions.

RBs -- In: (4) Fred Jackson, C.J. Spiller, Tashard Choice, Corey McIntyre. Out: Johnny White, Zach Brown. Analysis: This position hasn’t changed much throughout the offseason and training camp. Coach Chan Gailey is very familiar with Choice going back to their days together at Georgia Tech, which gives Choice the edge over White.

WRs -- In: (6) Stevie Johnson, Donald Jones, David Nelson, Derek Hagan, T.J. Graham, Ruvell Martin. Out: Kamar Aiken, Marcus Easley, Naaman Roosevelt. Analysis: The real question here isn’t which receivers the Bills will keep, it’s how many. Do they keep five or six? If it’s six, Martin has the upper hand. But it’s no guarantee that the Bills will keep six with QB Brad Smith also on the roster -- Smith can play WR in a pinch, as he proved last year.

TEs -- In: (2) Scott Chandler, Lee Smith. Out: Kevin Brock, Dorin Dickerson. Analysis: Dickerson will either be one of the final players on the roster or one of the last players off of it. The H-back brings some interesting tools to the table, but with Buffalo’s improved depth he may be a bit of a luxury.

OLs -- In (9): Cordy Glenn, Andy Levitre, Eric Wood, Kraig Urbik, Erik Pears, Chris Hairston, Chad Rinehart, Colin Brown, Sam Young. Out: Mark Asper, James Carmon, Zebrie Sanders, David Snow, Keith Williams. Analysis: Asper and Sanders, both 2012 draft picks, have been disappointing. It’s possible Sanders could be kept around as a long-term project, but the practice squad seems more likely.

DL -- In (8): Mario Williams, Marcell Dareus, Kyle Williams, Mark Anderson, Spencer Johnson, Dwan Edwards, Chris Kelsay, Kyle Moore. Out: Robert Eddins, Alex Carrington, Jarron Gilbert, Kellen Heard. Analysis: Heard and Gilbert both have a chance of sticking, but they may be victims of the numbers game. Buffalo’s defensive line depth is as good as it’s ever been, putting them in a tough position.

LBs -- In (7): Arthur Moats, Kelvin Sheppard, Nick Barnett, Kirk Morrison, Bryan Scott, Tank Carder, Nigel Bradham. Out: McKillop, Chris White. Analysis: The Bills have been giving Morrison more practice time in the middle on the second team in recent weeks, which doesn’t appear to be a good sign for McKillop. He previously ran with the second team at the "mike" linebacker spot. McKillop could stick around due to his abilities on special teams.

DBs -- In (10): Stephon Gilmore, Aaron Williams, Leodis McKelvin, Terrence McGee, Ron Brooks, Justin Rogers, Jairus Byrd, George Wilson, Da’Norris Searcy, Delano Howell. Out: Cris Hill, Nick Saenz, Isaiah Green, Josh Nesbitt. Analysis: Howell is the lone question mark here. Did he force his way onto the roster with impressive performances in preseason games? Or is he not experienced enough to crack the 53-man roster? It could go either way.

Special teams -- In (4): Brian Moorman, Rian Lindell, Garrison Sanborn, Potter. Out: Shawn Powell. Analysis: It’s not easy to keep an extra kicker, but it looks like Potter may force the Bills’ hand this year. He’s been excellent on kickoffs and could save a lot of wear and tear on Buffalo’s special-teamers in kick coverage.

For more updates on the Bills follow correspondent Mark Ludwiczak on Twitter @CBSSportsNFLBUF and @MarkLud12.