PHILADELPHIA (973espn.com) — The euphoria of a walk-off win over a division rival morphed into the realization that the Eagles will be without Darren Sproles for the rest of the season.

Both parts of the much-ballyhooed "21-Pony" formation that was the talk of the Eagles' offseason are now essentially kaput for 2017.

The experiment of putting undersized rookie running back Donnel Pumphrey on the field at the same time with Sproles was designed to create untenable matchup problems for the opposing defense and was largely done in by the ineffectiveness of Pumphrey during the training camp and the preseason.

A torn hamstring in practice then sent the rookie, who was being redshirted on the back end of the Eagles' roster, to injured reserve. He'll be joined there by Sproles, who suffered a broken arm and a torn ACL during the same play in Sunday's 27-24 win over the New York Giants, something coach Doug Pederson confirmed at his Monday press conference.

Sproles' left forearm was inadvertently kicked as Giants safety Darian Thompson flew by while making a tackle. The veteran immediately grabbed his left knee as he hit the turf but the Eagles' announced it as a wrist injury which confused many.

Turns out it was both as Sproles broke his arm and tore the ACL, ending his season, likely his tenure in Philadelphia, and perhaps even his career.

At 34, Sproles is on his last year of his contract with the Eagles and has intimated retirement in the past while Philadelphia clearly selected Pumphrey during the draft in the hopes he could replace Sproles in 2018.

The latter is unlikely since Sproles is essentially the team's best runner, pass receiver and pass protector in the backfield and doubles as a Hall of Fame-level punt returner.

"It's a devastating loss obviously," Pederson admitted. "...He's a great man, a great leader, well-liked on this team and in this locker room and in this community. That's hard to replace and guys are just going to have to rally."

Second-year man Wendell Smallwood got the majority of snaps Sunday after Sproles' absence and the learning curve of a three-down back is going to be sped up in the coming weeks for the West Virginia product.

Also in the mix are veteran bruiser LeGarrette Blount, rookie Corey Clement and perhaps even Byron Marshall, who could be elevated from the practice squad.

"It's going to have to be that next-man mentality," the coach said.

Smallwood and Blount both carried it 12 times against the Giants while Clement had six totes and they all combined 160 yards with Blount and Clement each finding the end zone. The snap count was Smallwood at 43 followed by Blount with 22 and Clement with seven. Sproles was in on five snaps before being injured.

Torrey Smith, meanwhile, handled the punt returns, something he hadn't done since high school.

"He has done it in practice in the past," Pederson said of Smith taking over the PR duties. "He's definitely a sure-handed guy back there so right now he's the next guy."

-John McMullen covers the Eagles and the NFL for 973espn.com. You can reach him at jmcmullen44@gmail.com or on Twitter @JFMcMullen

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