The Redskins got the reality check that almost had to arrive sooner or later. So, it’s probably just as well that their 20-13 loss to the Philadelphia Eagles came early in the season, while their record is still 3-2.

A winning record is a fine psychological cushion, especially when an improving but still rebuilding team has to cope with problems that, since preseason, have been simmering issues. And now have arrived full-blown.

Hope, they say, isn’t a strategy. The Redskins have much improved their defense. They have added depth at running back. They’ve added 500 wide receivers in an effort not to remain a league joke at a position that’s now so vital in a wide-open, run-and-gun NFL. But in some vital areas, they simply had to hold their breath; you can’t fix everything at once.

The Redskins hoped a thin offensive line wouldn’t suffer injuries. They hoped that their defense was vastly better, not just much improved. And they hoped that Rex Grossman would be a new man in a Shanahan offense. Now, all three issues will suddenly be under the microscope simultaneously.

On Sunday, guard Kory Lichtensteiger suffered a serious knee injury that may put him out for the season. Offensive tackle Trent Williams sustained a high ankle sprain that he called “excruciating” and which usually sidelines 300-pounders for at least a couple of weeks. Trying to sustain a running game, even at 1-5 Charlotte next week, will be a test. But, in the long run, forcing more offensive linemen onto the field, like versatile 320-pound second-year Erik Cook, who played creditably, actually creates more depth.

The loss of Williams was a particular setback because, for a fourth overall pick in the ’10 draft, he hasn’t developed quickly. Considered the heir to Chris Samuels (a third overall pick in ’00), Williams committed two penalties — holding and unnecessary roughness — in the Redskins’ first five plays. Talent, minor injuries and inconsistency have been his trademarks.

“I wanted to go through a whole year injury-free,” said Williams, who missed two games in ’10. “Somebody came down on it. I’ve never had this before but it’s very painful. To get hit with this is very discouraging.”

The Redskins entered the game with hopes that their No. 2 ranking in the NFL in points allowed was not a mirage. When they trailed 20-0 in the second quarter, flashbacks to the Eagles’ 59-point onslaught here last season came to mind. That defense was a total mess. This one, apparently, is just careless: They misplaced a half of football.

“The whole first half was mediocre, like we were going through the motions without intensity. We seemed flat,” safety LaRon Landry said. “We talked about it at halftime. It’s all about attitude.”

Landry, at least, found his and almost knocked Michael Vick out of the game with a tackle early in the third quarter. “Vick seemed groggy [after the play] like he was about to fall down,” said Redskins linebacker London Fletcher, who said that he and a couple of Eagles actually put their hands on Vick so he wouldn’t collapse. “He didn’t look too good initially.” Vick later said he had dirt in his eyes.

Some thought Fletcher might have made the hit. “London? It was me. Get your eyes right,” said Landry, incredulous. “At first, I looked down and thought: ‘Okay, he’s out of this. Here comes the backup.’ But he’s a competitor and he came back.”

Actually, backup Vince Young did enter briefly, throwing a gift interception into double coverage as he was tackled. Vick returned or, more likely, couldn’t be kept out.

“Give credit to the Eagles. Their backs were to the wall, their season on the line,” veteran Donte Stallworth said.

For the Redskins, this was an opportunity game with a huge chance to ruin Philadelphia’s season and stay in front of the NFC East. But in the NFL, where emotion and recklessness bordering on mayhem trump almost any other virtues, Philly faced a true desperation game. Bet on desperate.

Once the Redskins fell far behind, they rediscovered their defense and shut out the Eagles in the second half, something neither the ’09 or ’10 defenses likely would have done. “In the second half, the defense gave us so many chances” to get back in the game,Coach Mike Shanahan said.

That’s when the Redskins’ final area of perhaps-misplaced hope this season came into focus — at quarterback. In the third quarter, the Redskins had first downs at the Eagles 9-yard line and 18-yard line, yet came away with just three points. Before the period’s end, Grossman threw his third and fourth picks.

Those interceptions gave him a breath-taking 19 turnovers in less than eight full games since he replaced Donovan McNabb. Mind-boggling would be mild. We can only hope every word on Grossman that’s escaped the mouths of either Mike or Kyle Shanahan should not be taken entirely at face value but, rather, seen in the context of “best available alternative for now.”

Because if “Rex = solution” is what they really think, they might cut Unitas.

Grossman is game, accountable, throws a pretty ball and has genuine gunslinger hot streaks. But turnovers matter more than anything in the NFL. So, now, he can fulfill his natural destiny: nice, dangerous backup.

At least the suffering is over. Shanahan said all the sensible things coaches say when they want 48 hours to make absolutely sure a quarterback switch is correct. But it obviously is. Now, the Redskins can, with dignity and good conscience, give John Beck a full test. Whether Beck pans out or not, it had to happen, so, once again, better now than later.

Beck looked promising. But moving the ball decently in the fourth quarter against a defense that’s protecting a 14-point lead isn’t a real exam. First impression: He looks like Griese — mobile, smart, probably poised. But more like Brian Griese, who had a 45-38 career NFL record and an 82.7 rating, partly as a starter for Shanahan in Denver — not his Hall of Fame father, Bob.

Reality checks aren’t fun. Fantasy’s so much better. But, even after this loss, Redskins reality isn’t hard to bear. They came back to (sort of) make a game of it after trailing by 20 points to one of the NFL’s most talented, and most underachieving teams. Their offensive line will be a patchwork worry, at least until Williams returns. Their defense, after allowing 422 yards on its home field, may merely be quite good. But quarterback may get better.

All the basic signs of gradual long-term Redskin progress are still in place. But, sometimes, when you’re crawling toward the light from a dark place, you slip backwards along the way.