When MRob came back, he was an immediate upgrade to Coleman. Mike Rob is a much better lead blocker; he's still elite in that category. The other positive to having Robinson is that Lynch trusts him implicitly. They've even said that many times, Lynch just follows MikeRob as he trusts his vision. At times Lynch looked lost after Robinson was cut, and it seemed to hurt his vision. I haven't heard about anyone offereing Robinson a contract, and I get the impression from Robinson that he either wants to be a Seahawk or he'll bounce to NFLN. He is a great broadcaster and has a home whenver he wants it.
Coleman is more athletic. He's faster and can make a bit more happen with the football. Robinson even said on NFLN that Coleman is still a work in progress and that he thinks like a tailback still. When Coleman gets that fullback mentality down, he'll be damned good and will actually be a weapon at fullback.
I think Robinson would come back at a minimum, and I don't think contract has a whole lot to do with it at this point. My theory is that the coaching staff probably doesn't want to spend 2 roster spots on a fullback, and they are going to evaluate the younger guys like Coleman and Ware and see who is the best fit and who seems to have the highest ceiling. Like someone above said, Robinson is getting older and it's no guarantee that he will keep playing at a high level, even over the entire next year. Coleman and Ware have room to improve and are young and that's what our FO is looking for: youth and growth.