There's been a lot of talk this offseason about why the Eagles moved on from LeSean McCoy and signed DeMarco Murray (along with Ryan Mathews). One of the most commonly cited reasons relates to McCoy's playing style.
Shortly after McCoy was traded, Peter King reported Kelly made the move because "McCoy was too east-west of a runner for [Kelly's] taste." CEO and Chairman Jeffrey Lurie confirmed Kelly desire for a change in running style during the NFL owner's meeting. Kelly himself admitted the Eagles were looking for "a down-hill, one-cut runner" for their zone-scheme.
In hindsight, Kelly's preference shouldn't have come as a surprise. Here's an interesting quote from the then-Oregon Ducks coach back in 2008, as recently highlighted by Matt Lombardo of NJ.com. The context is Kelly explaining the zone read option during a lecture at USC seven years ago. Bold emphasis is mine:
"We tell the running back to read the first down lineman to the play side. If he expands in the gap, the running back hits the gap. The philosophy of the play is a tough running play. If the line can get up two yards on the defense, the back can, too. We want him to jam the ball into the hole and be a tough runner. We do not want a jingle-footed back trying to hit a home run. We want him to hit the ball into the line and get the tough yards. We are a blue-collar guy going to work. The line will have a hat on the five defenders in the box. The unblocked defenders on the perimeter are following the ballcarrier. If he gets downhill and runs hard, it is hard for them to make the tackle. However, if he jiggles in the hole, they will make the tackle.
When we talk to the back, we tell him it is speed through the hole, not speed to the hole. When the running back receives the ball, he is at 85-percent speed. As he gets the handoff and makes a decision to take the ball frontside or cut it back, he makes one cut. When he makes his cut to the line, he changes speeds and runs through the hole."
McCoy was criticized at times for his habit of losing yards by "dancing" in the backfield. This criticism can be a little bit harsh considering McCoy's great success with Philadelphia, but there is some legitimacy to it. McCoy led all NFL rushers in negative runs in 2014.
Whether the Eagles running style change pays off remains to be seen. There's no question the Eagles have a lot of talent at the running back position. Now it's up to Kelly, along with the players he picked, to prove that the change was worth it.