2015 Free agent running back options for the Chargers

Dec 28, 2014; Kansas City, MO, USA; San Diego Chargers head coach Mike McCoy leaves the field after the game against the Kansas City Chiefs at Arrowhead Stadium. The Chiefs won 19-7. Mandatory Credit: Denny Medley-USA TODAY Sports
Conclusion
The choice at running back will be interesting. The team likely will not go in the free agency market to pick up a back. They could look to add a back early in the draft though. They also could look to re-sign Ryan Mathews on an incentive filled deal.
If the Chargers were to sign one of the backs that were mentioned, we would get a little insight on how Mike McCoy would like to run his offense. If the team went with Ryan Mathews or Mark Ingram on offense, then we would lean on the run game a little more. If we went with Spiller or Bush, this team will be looking to let it fly.
Before running back is even thought about, the offensive line will have to be the number 1 priority. Create a solid group up front and we will be able to run with any of the guys mentioned.