Tony Romo plays the most important position and pulls down the biggest salary on the Dallas Cowboys, but he's not the guy who makes the difference with this year's team. DeMarco Murray is. He's more than merely the Cowboys' starting running back; he's the key to their success. Because if Murray can stay in the lineup ... and if the Cowboys can make a commitment to him and the running game ... they have a chance to do something they haven't the past three years. Make the playoffs. "We can be tremendously good if I stay in there for all 16 games," Murray said after practice Tuesday. "And somehow, some way, I'm going to try to make that happen." Good. Because in his two years with Dallas he spent too much time on the sidelines. He missed nine of 32 games, and while the Cowboys would love to feature him -- heck, they're 8-0 when he has 20 or more carries -- they must be aware of his history, too. A year ago, for instance, he missed six starts, and Dallas sank to 31st in rushing. Worse, its 1,265 yards were the second lowest in franchise history, and they had fewer attempts than everyone but Arizona. "We just weren't very good at it," tight end Jason Witten said, "and I think that's part of the reason our record was what it was." I won't argue with that. But that's about to change, with new offensive coordinator Bill Callahan doing the changing. Owner Jerry Jones put him in charge of the play calling because he saw where the Cowboys' pass-first approach was getting them -- which was back-to-back 8-8 finishes. So Callahan, who also coaches the offensive line, rolls out Murray, calls his number enough times to keep the defense honest and keep onrushing linemen off Romo and ... presto! Just like that, the Cowboys are a success.