Whether it was because he was limited in practice by a knee injury leading up to the game or because the Cardinals fell behind early and needed more of a pass blocker in the backfield, running back Kerwynn Williams, who had performed admirably the previous two weeks, totaling 175 yards on the ground, was hardly a factor Week 16 against Seattle, getting two carries for 4 yards.
Instead, Stepfan Taylor was the lead ball carrier. Of course, he wasn't so effective in the role, picking up 19 yards on 11 carries, but that's bound to happen for any running back going against the Seahawks. He did at least have 25 yards on two catches. Marion Grice and Robert Hughes also each got a carry, but they haven't been as much of a factor with Andre Ellington out.
Williams seems to be the best rusher of the group and the one you'd prefer to see get the carries in Fantasy, but if the Cardinals are that willing to abandon him when the score isn't in their favor, you can never feel confident playing him in Fantasy. Especially now that the Cardinals are down to their third quarterback, the score isn't going to be in their favor so often.
Week 17 at San Francisco should be a more competitive game, but given that the 49ers are tough against the run as well, you should probably pass on Williams for the season's final week.