Williams is not a bad guy to trot out there either. Jones is good in some situations. he's explosive. I do not buy the PFF ratings, it's a case where their numbers don't match what I've seen. not by a long shot. I have never seen Jones come close to attacking a blitzer and stoning him like Williams has done repeatedly. I haven't seen him make a block of note all year in Pass protection.
Anyway, the last game, expecting run, Williams gets 6 yards. Jones come in for carry 2 and gets eaten up at the line. Lets not act like Williams serves no purpose and Jones is the be all and end all. He has his limitations as well. They're both capable backs. Early in the seasons Jones wasn't even an option. He also doesn't have a history that says, line me up and give it to me 25+times a game either. Then the situations, as swhitset said, dictated something else. I'm sure Jones is going to see the ball more as the season progresses, but I'm not sold on him being the feature back out of the gate as I don't think he'd hold up.