Matt Slocum/Associated Press

The Philadelphia Eagles may have stolen reigning NFL rushing champion DeMarco Murray out from under the Dallas Cowboys, but which of these bitter NFC East rivals will wind up having the last laugh?

After trading LeSean McCoy to the Buffalo Bills, landing Murray in free agency seemed like a major coup for the Birds. However, there are plenty of reasons to be concerned about the two-time Pro Bowl running back's condition before he ever plays a down for Philly.

DeMarco Murray Career Rushing Stats YR GMS ATT YDS AVG TD FUM 2014 16 392 1,845 4.7 13 5 2013 14 217 1,121 5.2 9 3 2012 10 161 663 4.1 4 3 2011 13 164 897 5.5 2 1 NFL.com

Are the Eagles getting the Murray who ran for 1,845 yards in 2014 and was named the league's Offensive Player of the Year? Or is this a broken-down version who will never again be the same after enduring a punishing workload?

We're talking about the 370-carry theory, more commonly known as the Curse of 370. The hypothesis of the now 11-year-old study by Aaron Schatz of Football Outsiders is this: "A running back with 370 or more carries during the regular season will usually suffer either a major injury or loss of effectiveness the following year."

Admittedly, it's not an exact science. For instance, Hall of Famer Eric Dickerson was a notable, recurring outlier. The author also noted that the number 370 is not magic but "a close approximation of the tipping point." Furthermore, there could be a variety of explanations for injuries or declining production that go beyond overuse.

Yet you don't have to be into advanced statistics or possess a medical degree to reach the conclusion that an overworked ball-carrier is a less effective ball-carrier. Curse or no, there's reason to believe Murray's usage last season may have taken its toll.

Murray carried the ball 392 times during the regular season in 2014, the seventh-highest figure in NFL history and well over the 370 threshold. Five of the six backs ahead of Murray on that list experienced a measurable dip in production, Dickerson being the lone exception in 1985.

North of 392 Carries PLAYER YR ATT AVG NEXT YR GMS AVG Larry Johnson (KC) 2006 416 4.3 2007 6 3.5 Jamal Anderson (ATL) 1998 410 4.5 2003 2 3.1 James Wilder (TB) 1984 407 3.8 1985 16 3.6 Eric Dickerson (STL/IND) 1986 404 4.5 1987 12* 4.6 Eddie George (TEN) 2000 403 3.7 2001 16 3.0 Gerald Riggs (ATL) 1985 397 4.3 1986 16 3.9 Pro-Football-Reference

That only begins to tell the story. Murray tacked on 57 receptions as well, giving him 449 touches for the season—the sixth-highest of all-time. Of the top five, only San Diego Chargers great LaDainian Tomlinson managed to escape to the law of diminishing returns in 2003.

North of 449 Touches PLAYER YEAR TOUCHES YPC NEXT YR GMS YPC James Wilder (TB) 1984 492 3.8 1985 16 3.6 Larry Johnson (KC) 2006 457 4.3 2007 8 3.5 Eddie George (TEN) 2000 453 3.7 2001 16 3.0 LaDainian Tomlinson (SD) 2002 451 4.5 2003 16 5.3 Edgerrin James (IND) 2000 450 4.4 2001 6 4.4 Pro-Football-Reference

And in addition to Murray's regular-season totals, he tacked on another 44 carries and four receptions during the playoffs for the Cowboys. All told, when you count snaps that went no-play due to penalties, Murray touched the ball over 500 times during the 2014-15 campaign.

How could you not be at least a little concerned? There's evidence that Murray's workload was already beginning to impact his performance last season.

Brandon Wade/Associated Press

Murray's yards per carry decreased steadily as the year went along. For the month of September, he averaged a lofty 5.4 and was still going strong in October at 4.9 per attempt. In November, Murray was down to 4.4 yards per carry, and by December, his average dropped to 4.0—roughly the minimal expectation.

To be fair, some of that is a reflection of opposing defenses keying in on stopping Murray. Then again, you can also go back to the tape and see Murray wasn't running away from defenders or breaking as many tackles, either.

Will those issues linger into 2015?

On one hand, the Eagles have been the healthiest team in the NFL over the past two seasons, based on another Football Outsiders stat, adjusted games lost. Much of the thanks goes to the organization's sports science program under head coach Chip Kelly. The club also signed two-time 1,000-yard rusher Ryan Mathews from the Chargers to help share the load and keep Murray fresh.

Of course, Murray isn't exactly a young player, so it's difficult to say whether he'll bounce back. He's 27 years old, and a recent study by ESPN Stats & Information showed that running back decline begins at 28—which means if the curse hits, Murray's best days are already behind him.

Nor has Murray been a picture of health throughout his career. 2014 was the first time he suited up for all 16 games, so it wouldn't be a surprise to see him on the injury report regardless of how many times he touched the ball the previous season.

None of which is to suggest that the Cowboys didn't make a mistake in allowing Murray to get away, either. They may have trouble replacing him with some combination of an unproven Joseph Randle and oft-injured Darren McFadden.

But the Eagles aren't necessarily coming away with a star here.

Murray was voted the fourth-best player in the NFL by his peers heading into 2015, which shows there's a ton of respect for his smashmouth, take-no-prisoners approach to pounding the rock.

You simply have to wonder how much he has left in the tank.