Initially, I would say that they can split carries 50-50, but then I think of Madden always saying that "when a team says that it has two backs, that really means that it doesn't have any." One of them is going to have to be the guy that gets 70% of the downs, including the ones at crunch time. I think that Marshawn is the better runner, but Lynch's versatility has been very valuable in the current offense.