Tight end Jordan Reed hangs his head after the Redskins failed to connect on a fourth-down pass late in the fourth quarter against Dallas in Week 2. (Toni L. Sandys/The Washington Post)

Redskins Coach Jay Gruden confirmed Thursday that tight end Jordan Reed, the team’s leading receiver, has been diagnosed with a concussion and remains in the NFL’s concussion protocol.

While Gruden didn’t rule out the possibility of Reed competing in Sunday’s NFC East clash with the Philadelphia Eagles, it’s exceedingly unlikely, if not impossible, that he would clear all five stages of the mandatory concussion regimen, in which an independent doctor signs off on a player’s gradual return to activity.

This is Reed’s fifth diagnosed concussion and at least his sixth overall, by his own admission. He previously acknowledged not reporting one of two concussions suffered in 2013.

Asked whethr the team was concerned about the cumulative effect of Reed’s multiple concussions, Gruden said, “That’s a little bit out of my league. We have to just take each individual injury for what they are. We let the independent doctor and our doctors decide on how severe they are. … We obviously want him to get well. He’s a very important part of our offense, but we also want him to get better from a personal standpoint.”

Reed suffered the concussion during Sunday’s victory over Baltimore but didn’t report symptoms until players regrouped for meetings Tuesday at Redskins Park.

Gruden said that neither he nor the coaching staff nor NFL observers detected any signs of a concussion from the sideline or from suites upstairs during Sunday’s 31-20 victory over Baltimore. “He took a couple of shots but none that were alarming as far as we were concerned, as far as keeping him out of the game,” Gruden said.

At 6 feet 2 and 246 pounds, Reed, 26, leads all Redskins receivers with 33 catches for 316 yards and two touchdowns.

The Redskins have depth at tight end, with 11-year veteran Vernon Davis and sixth-year veteran Niles Paul on the roster. But Gruden made clear that he wasn’t counting Reed out for Sunday, when the 3-2 Redskins will host the 3-1 Eagles at FedEx Field.

“We’re still waiting to see, so it’s a tricky situation,” Gruden said. “I think we’ll be okay. Obviously we want him back. He’s a big part of our offense and a great player, but the other guys are ready to step up. [Jamison] Crowder will get more looks, DeSean [Jackson], Pierre [Garcon], Vernon, Chris [Thompson] — so we have good enough players.”

Left tackle Trent Williams, who has played alongside Reed since the Redskins chose him in the third round of the 2013 NFL draft, said that the Florida product’s health was the most important issue at the moment.

“As a friend, I’m extremely concerned for his health,” Williams said. “Concussions are nothing to play with, especially for him. He got up and finished the game. I think that speaks volumes about his character and his toughness. But as you know, it’s well documented that concussions can have long-term effect on people, so it’s not even about a game anymore. It’s about him returning back to full health before he even puts that helmet back on.

“It’s hard to replace a guy like that if in fact we have to replace him. It’s definitely tough; he brings mismatches all over the field. But it’s the NFL, man. Everybody has a key player go down at some point, and the next player just has to step up. We got talent at that position, so hopefully we won’t feel the drop-off as bad.”

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