By Mike Fisher

FRISCO, Texas (105.3 THE FAN) – Dallas Cowboys standout defensive lineman David Irving may be shut down for the remainder of the regular season, multiple sources tell me, the result of a lingering concussion sustained at the end of the Nov. 30 victory over the Redskins.

gettyimages 630227242 Sources: Cowboys DL David Irving Could Miss Both Upcoming Games

David Irving  (Photo by Tom Pennington/Getty Images)

Moments after releasing my 105.3 The Fan report, Irving himself tweeted, “Mentally I’m fine … I’m still having headaches every day. It’s hard to put a finger on how long I’ll be out. I’m taking it day by day.”

One more loss will officially eliminate Dallas from playoff contention, and that could make Week 17 at Philadelphia meaningless in every way — including in trying to hurry the talented Irving back onto the field. But I’m told it’s now “likely” that he’ll miss this Week 16 battle against the Seattle Seahawks on Sunday.

Irving has not played or practice since that Nov. 30 game, though on two occasions the team has allowed him to “do some things” on the sideline without a helmet.

The good news with Irving, according to one source close to him, is that this is his first “serious concussion,” so there is ideally not long-term concern about his health. The bad news for the Cowboys – and for Irving, who desperately wants to contribute to Dallas’ 8-6 improvement – is that they are without his impactful star quality. When healthy, he teams with first-time Pro Bowler Tank Lawrence as one of football’s best one-two-punch pass rushers.

But he’s not healthy.

In the words of multiple people who care about him, and now in the words of David Irving himself.