(On a side note, check out the win probability graph at pro-football-reference.com. That was one of the craziest endings I've seen in a while.)
In the week leading up to the game, I posted a complaint about the play calling. I highly doubt that Kyle Shanahan reads this site, but my complaints were answered. The Redskins ran the ball 40 times, sticking with it even after a difficult start, and that was key. However, just as the decision not to run the ball in a key situation ultimately doomed the Chargers, it almost doomed the Redskins. Throwing the ball from your own end zone is never a good idea, and when you have arguably the top running offense in the league (1st in yards per attempt) the foolishness is magnified. Gift wrapping 7 points against a quality football team should have spelled disaster. Between that, the continued failure to get touchdowns on drives, and the two blocked field goals, the Redskins did their best to give away the game. The reasons they did not are as follows:
1. Sticking to the rushing attack, and using all of the available weapons. I've already hit on the first part of this. The second part is equally important. Who thought, going into the game, that the Chargers would need to defend Darrel Young? I'm guessing nobody. But he is a weapon (albeit of a different nature) every bit as much as RGIII, Helu, and Morris. No, he isn't going to break a 50 yard run or rush for 200 yards in a game. But he has a key role in this offense, as anyone who watches the triple-option offenses in college football (or remembers Cory Schlesinger at Nebraska) could tell you. I honestly believe that the Redskins could throw the ball 8-10 times a game and win. Having to defend all of the backfield options (RGIII, Morris, Helu, DY, and Moss/Reed/Morgan) would be almost impossible, even with 9 or 10 in the box. Since RGIII can easily see when the opponent is stacking the box and audible to an outside receiver (and since Garcon has shown he can win one-on-one battles) getting all those players on the field could be almost unstoppable. The added benefit to this is that the more the running game is used, the less the defense is on the field, and everyone prefers their defense on the sidelines.
2. Aggressive defensive play. The defense gives up yards in chunks. That's a bit of a problem. But there is another side to it that was on display yesterday. One of the main reasons why the defense gives up so many yards and big plays is because of aggressive play. The players are encouraged to be aggressive, and because they aren't elite-level players for the most part (with the exceptions of Kerrigan and maybe Orakpo, certainly Orakpo before last year), they give up big plays. But when the field is shortened like in the late game yesterday, that aggressiveness can pay off. It did. With no chance of a receiver running wide open down the field, the defense held. In fairness, it should also be noted that the defense has played very well in three of the last four weeks: holding the Cowboys to their lowest yardage total in 45 games (and essentially 17 points, taking away both kick returns), giving the Redskins 14 points and holding the Broncos for much of the game, and then holding the Chargers to 17 points. Even the Bears game wasn't as bad as the score makes it look; the Bears only gained 359 yards in total offense, allowed only 34 (even though an interception gave the Bears a short field) and scored a touchdown of their own. The defense isn't dominant, but it isn't the weakest unit on the team either. That (dis)honor clearly goes to special teams.
3. Winning the turnover battle. The Redskins are 2-0 this season when winning the turnover battle. They are 0-4 when losing it. The defense has gotten a turnover in every game, and multiple turnovers in 4 games. If the offense can eliminate mistakes going forward, this could be a key stat in another late run. If the offense continues to give the ball up (also at least one every game, with multiple turnovers in 4 games) the Redskins will struggle to beat anyone.