The Redskins' offensive line, operating these past four games without its starting left tackle, Trent Williams, suffered a major setback during Sunday's 31-23 loss to Arizona, with center Spencer Long diagnosed with a concussion following a hard hit that also injured his shoulder. Coach Jay Gruden said after the game, which dropped the Redskins to 6-5-1, that Long had been placed in the NFL's concussion protocol, a five-step process of rest and gradual return to competition that puts his status for Sunday's all-important NFC East game at Philadelphia in doubt. Also, safety Will Blackmon, who has been playing with a broken thumb, is undergoing tests for a stinger (a general reference to an upper arm or shoulder injury involving possible nerve damage) and a possible concussion. Long and Blackmon were the only players Gruden cited in his postgame injury report, although left tackle Ty Nsekhe briefly left the game with an ankle injury but returned, and defensive end Ricky Jean Francois asked for a trainer after the game to evaluate a sore foot. Long was replaced during the game by eight-year NFL veteran John Sullivan, 31, who played seven seasons with Minnesota before being signed as a free agent by the Redskins in September after starting center Kory Lichtensteiger was placed on injured reserve. Quarterback Kirk Cousins praised the job Sullivan did Sunday afternoon on no notice, calling the transition at center seamless. Still, losing the 6-foot-5, 324-pound Long for any length of time would be cause for concern. "They're all banged up," Gruden said on Sunday, asked about the offensive line's health heading into the final four games of the season.Read more on NewsOK.com