The ever-dramatic Washington Redskins upset the NFL apple cart once again yesterday when coach Mike Shanahan announced Rex Grossman as his starter for the rest of the season, beginning with tomorrow’s game at Dallas.

McNabb will be the No. 2 quarterback against the Cowboys, then drop to No. 3 behind Grossman and John Beck for the final two games of the season.

And after that?

“I also told him,’’ Shanahan said, “that I cannot guarantee him that he will be back next year.’’

That’s how far the 34-year-old, six-time Pro Bowl quarterback has fallen. The player acquired with such fanfare in an April trade — the quarterback who would do for Shanahan in Washington what Elway did for him in Denver — is benched in a season in which he has been woefully inconsistent, throwing a career-high 15 interceptions and ranking 25th in the NFL with a 77.1 rating.

McNabb’s performance has the coach leaving all options open for 2011. Shanahan said he had been planning to make the move after the Redskins (5-8) were mathematically eliminated from the playoffs, which happened last weekend after a 17-16 loss to Tampa Bay.

McNabb did not comment. McNabb’s wife abruptly canceled a scheduled interview with the Associated Press in which she planned to promote a charity event involving NFL wives.

Grossman did speak, however, and he’s aware that fans and pundits nationwide are ridiculing his promotion.

“I think everybody has doubters,’’ said Grossman, who led Chicago to a Super Bowl during the 2006 season but has thrown 33 touchdown passes and 36 interceptions in 31 career starts. “I’m human. How could you not be motivated to show everybody who’s mocking this, or talking on the radio or TV thinking they’re smart?’’

Ryan: ‘I never knew’ Jets coach Rex Ryan reiterated that he knew nothing about the wall of players that was formed on the sideline last Sunday against Miami, during which assistant Sal Alosi tripped the Dolphins’ Nolan Carroll. “The facts are the facts,’’ Ryan said. “I never knew, so it’s easy to stand up here and tell you that. I’m not a guy that lies about anything. I’m just speaking the truth. If that amazes people, it amazes people.’’ . . . Defensive lineman Trevor Pryce will not play in the Jets’ game at Pittsburgh tomorrow because of an injured hip. Cornerback Darrelle Revis was limited in practice, but is listed as probable with a sore right hamstring. Wayne Hunter is going to start at right tackle, filling in for injured Damien Woody. It will mark the first time Hunter is starting in seven seasons — as well as the first game in nearly three years that the Jets won’t have all five of their starting lineman playing . . . Steelers safety Troy Polamalu missed practice for the third consecutive day because of a strained right Achilles’ tendon and a sore calf and is likely to miss the game . . . Steelers linebacker James Harrison will use money given him by fans to help pay his NFL fines to throw a Christmas party for needy children and their families. As Harrison accumulated $125,000 in fines for four infractions, fans began sending him money to help pay them. Many were sent anonymously, so Harrison could not return them. Last month, Harrison started the James Harrison Family Foundation, a nonprofit group that will assist children. The foundation’s first event will be a brunch with Santa Claus at Heinz Field today.

Mulling Metrodome A Vikings executive said the team is concerned about the safety of the Metrodome after a winter storm caused the building’s roof to collapse, but he didn’t rule out the team playing there next season. The Vikings have long pursued a new stadium paid for mostly by taxpayers, and next year is the final year of their lease on the Dome. “Some people would say, ‘Well, a couple of shingles come off the roof you don’t build a new barn,’ vice president Lester Bagley said. “Well, the roof collapsed. We have concerns about the safety of the facility going forward.’’ Bagley said the Vikings are focused on Monday night’s game with the Bears at the University of Minnesota’s TCF Bank Stadium. The game will mark a return to outdoor football in Minnesota after the Vikings spent the past 29 years in the Dome . . . Vikings receiver Percy Harvin says he’ll “definitely’’ play Monday after missing the last two games because of migraine headaches.

O’Hara seems to be OK It appears likely that two-time Pro Bowl center Shaun O’Hara will play for the Giants against the Eagles (9-4) after missing six games with a sprained right foot. If O’Hara starts, Rich Seubert would move back to left guard. The Eagles listed Pro Bowl cornerback Asante Samuel (knee) and Pro Bowl wide receiver DeSean Jackson (toe) as questionable, although both are expected to participate . . . The Jaguars re-signed veteran Todd Bouman, the same day they listed David Garrard as questionable for tomorrow’s critical game at Indianapolis. Garrard tweaked his hamstring Thursday and was limited in practice yesterday. Former Bills quarterback Trent Edwards is Garrard’s backup. The Jaguars placed cornerback Terrence Wheatley (hamstring) on injured reserve to make room for Bouman. The Jaguars will also be without two defensive starters, linebacker Justin Durant (groin) and safety Courtney Greene (left shoulder) . . . Seahawks receivers Mike Williams (foot and ankle sprains) and Ben Obomanu (right hand laceration) will return tomorrow against the Falcons . . . A doctor will be at Matt Cassel’s side in St. Louis tomorrow to provide final advice on whether Kansas City’s quarterback should play 11 days after an emergency appendectomy.