Envisioning Chip Kelly's All-Star Backfield

When it comes to building NFL rosters, there's the standard way of operating, there's the unorthodox way of operating and then there's the Chip Kelly approach. 

In two years since Kelly took over as head coach of the Philadelphia Eagles, Philly has parted ways with two Pro Bowl quarterbacks, a Pro Bowl running back and two Pro Bowl wide receivers. Replacing Michael Vick, Nick Foles, LeSean McCoy, DeSean Jackson and Jeremy Maclin? Sam Bradford and a bunch of running backs.

As Phil Sheridan of ESPN.com wrote, "The bigger question is whether Kelly actually improved the Eagles. Different isn’t exactly better."  

Just this week, Kelly has signed two starting-caliber backs—the league's reigning rushing champion and Offensive Player of the Year, DeMarco Murray, and former No. 12 overall draft pick Ryan Mathews. 

Throw in Darren Sproles, whom they acquired from the New Orleans Saints last offseason, and Kelly now has three running backs who have the words "Pro Bowl" on their resumes.  

Back	Starts	YPA	TD	Avg. salary
1. DeMarco Murray	47	4.8	29	$8.4M
2. Ryan Mathews	53	4.4	24	$3.8M
3. Darren Sproles	19	5.2	44	$3.5M
4. Chris Polk	0	4.7	7	$1.5M

That wouldn't have been unusual 30 years ago, when teams ran as much as they threw and running backs won the MVP almost as often as quarterbacks. Nowadays, backs have become devalued as a result of an increased emphasis on the passing game. 

As a result, we've gone back-to-back years without having a running back selected in the first round of the draft and are seeing 1,000-yard runners like Justin Forsett and Knowshon Moreno settle for the types of contracts good kickers and punters often receive. 

But things are different in Kelly's world. His offensive system emphasizes the run, which is why the Eagles have handed the ball off more than anyone else in the conference the last two years. 

Team	Carries
1. Philadelphia Eagles	815
2. Seattle Seahawks	791
3. New York Giants	783
4. Dallas Cowboys	782
5. Green Bay Packers	773

You can see what Kelly's getting at here. 

Murray is a tough but smooth, one-cut runner with good vision and the ability to grind out extra yards. He can carry the load if required because he's somewhat of a jack-of-all-backfield-trades.

Mathews is about the same size and also spends the majority of his time between the tackles. He possesses similar speed and a similar playing style, but there's nothing wrong with having two tough backs in this age of platoons. 

Kelly knows it's about mixing and matching. He realizes that both Murray and Mathews have dealt with plenty of injuries, and Murray is coming off a season in which the Cowboys worked him like a mule.

With both guys spelling each other and Sproles—a versatile wheel-route king with game-changing speed—contributing as a change-of-pace back and/or a receiving option out of the backfield, Kelly will have the ability to keep his running backs fresh throughout the year. 

Date	Player	Injured	Missed
Sept. 2010	Mathews	Ankle	1 game
Nov. 2010	Mathews	Ankle	3 games
Nov. 2011	Mathews	Groin	1 game
Dec. 2011	Murray	Ankle	3 games
Dec. 2011	Mathews	Calf	1 game
Sept. 2012	Mathews	Right clavicle	2 games
Oct. 2012	Murray	Foot	6 games
Dec. 2012	Mathews	Left clavicle	2 games
Oct. 2013	Murray	Knee	2 games
Sept. 2014	Mathews	Knee	7 games
Dec. 2014	Mathews	Ankle	3 games

The way I see it, Murray is the guy. While Kelly has stated that the plan is to spread it around, per USA Today's Tom Pelissero, Murray's the man making $8 million a year. He led the NFL in rushing by a 484-yard margin last season. 

Team	Total
1. Minnesota Vikings	$18M
2. Philadelphia Eagles	$17M
3. Buffalo Bills	$11M
4. Chicago Bears	$10M
5. Seattle Seahawks	$10M

Mathews will be able to contribute when the Eagles are looking for something similar and Murray is either tired, hurt or struggling. But he's also a $3.8 million-a-year Murray insurance plan, which makes a lot of sense when you consider how much Kelly relies on the run and everything Murray has been through. 

Look no further than what Football Outsiders calls the "Curse of 370," which, based on countless examples, posits that "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, unless he is named Eric Dickerson."

Murray ran the ball 392 times in 2014, which was the seventh-highest total in NFL history. 

The balance is necessary, and it also takes extra pressure off of Sproles, who will be 32 in June. With a light workload last year, the former Charger and Saint averaged a stellar 5.8 yards per carry. He picked up 10 or more yards on 24 of his 57 touches. 

All of it gives Philadelphia an advantage it didn't have when he was hurt or struggling in recent seasons. They had the bruising Chris Polk in that extra slot last year, but he doesn't have as much experience, and he averaged just 3.7 yards per carry in relief of McCoy. 

Murray and Mathews run more like Polk than McCoy, who made a lot of plays with his uncanny ability to make defenders miss. He possessed a stronger ability to freelance and bust runs outside, but that comes with a risk.  

McCoy lost yardage a league-high 42 times and on 13 percent of his carries in 2014, while Murray did so only nine percent of the time. In that respect, Kelly's such a strong proponent of his system that he might prefer his new M&M duo. Murray and Matthews might both be a little more disciplined when it comes to hitting the designed holes. 

That ability to improvise was, of course, a big reason why McCoy was the league's top rusher in 2013 and finished third in the league in that category despite dealing with a slew of offensive line injuries in 2014. He turned a closed hole into a big gain, as we saw with this 21-yard run around the edge Week 17 against the New York Giants: 

NFL Game Pass

That doesn't mean Murray can't bounce runs outside and make guys miss in the open field. We saw him do exactly that on a 26-yard run against the Green Bay Packers in his last game with Dallas:

NFL Game Pass

But you don't get as much of that with Murray or Mathews, which might mean fewer big gains if the line isn't crisp, but it also means fewer chances are taken.

Eagles fans will surely miss some of McCoy's open-field, ankle-breaking antics. But consider that, according to Football Outsiders, Eagles backs were stopped at or behind the line of scrimmage more frequently than the majority of NFL rushing attacks both in 2014 and 2013, when McCoy won the rushing title. 

That might explain why Kelly has stated he was looking for backs just like Murray and Mathews, per Carron J. Phillips of the Delaware News Journal: 

"

We faced him twice, and we got a chance to see him up close and personal to see what he can do. He's a physical downhill runner, and we're looking for a physical downhill one-cut runner, and both him and Ryan (Matthews) possess those qualities.

When you have a physical downhill running attack, you better have two of them. They're going to carry the ball, but they're also going to take a lot of physical shots. We want to be able to spread out the carries.

"

The Dallas offensive line had three Pro Bowlers last season, two of whom played interior positions. Without that line, Murray wouldn't have been close to as good. Same applies to Mathews in 2013. That year—his only full healthy season as a pro—he put together 1,255 yards on a stellar 4.4 yards per carry behind a line that Football Outsiders ranked third in the league in run blocking. 

The good news is the Eagles have one of the strongest lines in the league. Left tackle Jason Peters and left guard Evan Mathis were Pro Bowlers in 2013, and Pro Football Focus graded center Jason Kelce as the best center in football that year. In 2014, Peters and Mathis were both ranked in the top three at their respective positions by PFF, with Kelce and right tackle Lane Johnson also receiving strong grades. 

Strangely, according to NFL.com's Ian Rapoport, the Eagles are considering trading Mathis, who is 33 but has made back-to-back Pro Bowls. Without him, I'd be a little less confident in a running game that might rely heavily on that line to stay strong.

But at this point, we owe the benefit of the doubt to a coach whose offense ranked fifth in football last year despite using nine offensive line starters and getting disappointing results from McCoy and the majority of his peers. 

Brad Gagnon has covered the NFL for Bleacher Report since 2012.

Follow @Brad_Gagnon