A day after the Bears signed Michael Bush to a four-year contract and Matt Forte went off on a subsequent Twitter rant that may or may not have had anything to do with Bush's signing (depending on if you believe his followup tweet), Marion Barber, last season's backup to Forte, announced his retirement from the NFL. While Barber's presence on the roster would have been as competition for the backup spot, removing himself from the roster would on the surface seem to tip Forte's negotiations in his favor. Without Barber on the roster, if things stayed as they currently are, the Bears would move into camp with a top three of Bush, Kahlil Bell and Armando Allen, something Bears management might not want.

But there's another factor to consider here - Barber retired after only his seventh season in the NFL.

Now I know that Barber and Forte aren't the same player - one's a short-yardage back who's never had a thousand-yard season nor broken 250 carries or 300 combined touches in a single season. And the other just finished his fourth year on injured reserve, two one-thousand yard seasons (and a combined 74 yards away from four) and a combined 1237 touches.

But Barber's retirement should send a signal to Forte that while he wants a long term deal, Barber was only in the league three years longer (pending of course he doesn't get signed out of retirement), and serves to reinforce the shorter shelf lives of running backs in the NFL.

Let's consider another factor here. Barber started picking up a greater share of carries in 2007 when he went to the Pro Bowl with 975 yards and 10 TDs, a year after a 14 TD campaign. That was his third season - he remained a starter until 2010 and fell off pretty sharply, mustering only 3.51 yards per carry in his final two seasons. Forte's obviously performed better than that, but he's already taken a lot of pounding and a lot of hits in his career - about as many as Barber has in his career. And he's not as physical a runner as Barber is. How many more hits will he be able to take?

Barber hasn't been required to be the majority of the offense that Forte's had to have been to this point over his career, either. Will Forte's extra touches impact the length of his future career?

So my question to you is this: Who does Barber's retirement favor more - Forte and his leverage over the Bears' available roster spots, or the Bears and the contract length and amount they can offer?