As good as DeMarco Murray's numbers look so far this season, there's a bitter sweetness to the stat sheet. That’s because with every yard Murray gains, the odds of his remaining a Dallas Cowboy beyond this season decline in proportion.

Sure, it’s great to see the Cowboys finally buy into the running game. Yes, Murray is running “angry,” as one Fox broadcaster put it. After his 100-yard effort against the St. Louis Rams on Sunday, Murray became the third back in team history to have three straight 100-yard rushing games to start the season. (The other two were Tony Dorsett, 1981, and Emmitt Smith, 1995.) You have to like that company.

Murray has now proved that, when healthy, he’s one of the league’s few three-down backs. He can run. He can catch passes. He can pick up the blitz. You don’t have to take him off the field if you don’t want to, although given Murray’s injury history it wouldn’t be a bad idea on occasion.

So for now Murray, is the focal point of this Cowboys offense, which is strange to see and strange to say. If this were 1999, when running backs ruled NFL offenses, the massive contract extension that owner and general manager Jerry Jones shoveled toward left tackle Tyron Smith a couple of months ago would have been Murray’s. Or, we’d be talking about the Cowboys using the franchise tag next season on Murray instead of wide receiver Dez Bryant.

So why is Murray the odd man out? Money and the 21st century NFL, where passers and receivers rule.

Murray is playing like a man who knows he can cash in next offseason. This is the final year of his rookie contract. Put yourself in his shoes. Would you rather stay in Dallas or test the free-agent waters? Not an easy choice, especially given Jones’ track record as a general manager. Do you really trust Jones to keep accumulating the talent needed to get the Cowboys out of mediocrity?

Let’s say Murray wanted to stay. Now it comes down to money. Does Murray fit into the budget? Right now the Cowboys have $136.5 million committed to the 2015 salary cap. That includes Smith’s extension, which made him the highest-paid tackle in the game.

The 2014 NFL salary cap is $133 million. Last year the cap went up about $10 million. Many assume that the 2015 cap will go up at least $10 million, which would be about $143 million. Profootballtalk.com reported that according to NFL sources the cap could be $145 million in 2015 and $160 million in 2016.

Either way, you see the problem. Even if the 2015 cap is $145 million, right now the Cowboys only have about $9 million to play with. Sure, they can move some money around. But it’s going to take about $20 million — at least — to keep Bryant and Murray on the same team. The Cowboys seem to value Bryant more, thus the speculation around him and not Murray regarding a long-term deal or the franchise tag.

That’s the other issue. The passing game rules the NFL these days, and backs are considered more interchangeable. (That’s a better word than disposable.)

Even a back as talented as Murray is less valued when the Cowboys have two young backs on the roster. In 2015 Joseph Randle could handle the running and Lance Dunbar could handle the pass-catching. Don’t put it past Jones and company to go to a platoon.

Blame it on Bill Belichick, who has for the past decade shuttled backs in an out of an offense built around quarterback Tom Brady and a large group of receivers. Now everyone wants to do it because the Patriots won three Super Bowls doing it.

It may be that attitude, more than anything, that costs Murray a big deal in Dallas. With each passing yard, the price tag goes up.