Perhaps the law of averages goes a long way toward explaining the recent downturn in production for DeMarco Murray, who has averaged only 66 yards per game over the last three weeks.
Or perhaps its the absence of the fullback, Tony Fiammetta, or the star wide receiver, Miles Austin, who can discourage defenses from stacking the line. It all works together.
For the most part, the running game has been productive, even if the average is down. Last week, Murray's 12 carries produced gains of 7, 3, 5, 7, 6, -3, -3, 1, 4, 0, 6 and 5.
The negative runs and the no gain are a problem, but what's really missing are the long gains. In his first four games as the Cowboys' lead back, against St. Louis, Philadelphia, Seattle and Buffalo, Murray was busting long carries each week - 91, 26, 32, 25.
Even against Miami, Murray had an 18-yarder. But his longest against Washington was 8, and his longest against Arizona was 7.
"Last week we ran the ball efficiently, but no long runs," running game coordinator Hudson Houck said. "So the yards per carry were going to be down. The average is going to be down. But I think the success of each play, the four yards or more, was extremely high last week. We just didn't get any long runs, and that's where you get your average."
Again, it all works together. The shortage of long runs may have a lot to do with the absence of Fiammetta, and Austin being out might have allowed safeties to creep up to the line of scrimmage.
Last week, the Giants were able to stop the run while still playing their safeties back in coverage most of the time.
"Maybe that's moreso what we've seen," Houck said. "The team we're playing right now (New York) . . . Green Bay, they averaged 2.1 yards per rush against them, and that's not very good.
"They're pretty good against the run, even when it wasn't an eight-man front."