The Bears brought in RB Michael Bush, QB Jason Campbell and CB Kelvin Hayden just in case the injury bug hits again. Here is our breakdown of those players:

RB Michael Bush: Signed for $14 million, including $7 million in bonus money, the former Raider has already played a major role without doing anything. He gave the Bears leverage in contract talks with Matt Forte.

In their back pocket, they always had a player who started 16 games over three seasons, capable of catching, blocking and running. His role as relief back for Forte and short-yardage back could get him somewhere near 500 or 600 yards and plenty of first downs and touchdowns.

He's easily better than fumble-prone Marion Barber and the most talented backup running back they've had on the roster since the Super Bowl 1-2 punch of Cedric Benson and Thomas Jones in 2006. Fitting into Mike Tice's running game could be the biggest obstacle Bush faces. Bush is a power back who is at his best blasting through a quick-opening hole, but Tice's blocking schemes sometimes take a while to develop. So Bush may need to learn some patience before making his one cut and going.

QB Jason Campbell: Signed for $3.5 million and one year, the Bears hope they never have to use him. Like Bush, he's an insurance policy in case Jay Cutler gets hurt again as the Bears don't want a second straight season derailed by the lack of adequate backup.

As a proven starter, he's easily better than Caleb Hanie, the scapegoat for the Bears' collapse after Cutler's injury. Campbell has looked comfortable adapting to an offense that can have him throwing on the move -- something that previously wasn't considered a big strength.

CB Kelvin Hayden: Like with Bush and Campbell, he's already served a great purpose by inspiring starter Tim Jennings. When the Bears signed Hayden, who helped beat them with an interception return for touchdown in Super Bowl XLI, it meant stiff starting competition for Jennings.

Last season Jennings lost his starting job briefly for dropping certain interceptions, but has worked extremely hard in the off-season to sharpen his fielding and coverage skills, knowing he'd be in for a starting and/or roster fight with a player he once lost a job to in Indy. He's a big improvement over Zach Bowman, and another insurance policy at $605,000 against the salary cap.

Follow Bears reporter Gene Chamberlain on Twitter @CBSSportsNFLCHI.