Who will be the X factors this weekend?

After breaking down film and critiquing the teams playing in divisional games, Scouts Inc. tells you who the X factors will be in each game.

San Diego Chargers at Pittsburgh Steelers

Chargers RB Darren Sproles: He isn't a secret anymore, and this free-agent-to-be has officially burst onto the public scene after a spectacular all-around performance in San Diego's home victory over the Colts. Sproles' instant acceleration makes him extremely dangerous, and the Chargers are doing a very good job of getting him in a position to make plays. He can run between the tackles, but is certainly better attacking the edge. Plus, he is a very accomplished receiver on screens, which will be an especially useful tool to help slow down Pittsburgh's ferocious pass rush. Sproles could also see more action due to LaDainian Tomlinson's nagging groin injury. But will the elements or soft field surface at Heinz Field slow him down, and how will he handle his blitz pickup responsibilities against much bigger men like OLBs James Harrison and LaMarr Woodley?

More X Factors

Find out who Scouts Inc. thinks will be the X factors in the other three games. InsiderInsider

Steelers QB Ben Roethlisberger: Because of his somewhat reckless style, he is always a bit of an X factor. He is extremely talented and makes a ton of big plays, but he also tries to do too much at times and is not one to give up on a play. This trait is magnified because of his supporting cast. Pittsburgh has a marginal run game, and while the pass-catchers are solid, the protection is poor. Roethlisberger's offensive line is often overmatched, and that should be the case once again Sunday. Those are the situations when Roethlisberger tends to press and lose his patience or put the offense on his back. Matching this with the fact that he was last seen leaving Heinz Field on a stretcher with a concussion in Week 17 and it is very easy to understand why Roethlisberger is the ultimate X factor.

Scouts Inc. watches games, breaks down film and studies football from all angles for ESPN.com.