DETROIT -- The Washington Redskins learned a valuable lesson Sunday. They showed their typical resolve. Their quarterback showed a thing or two, leading a comeback.

But they couldn’t close out the game late, largely because of mistakes made earlier in a 20-17 loss to the Detroit Lions. You can’t go on the road and have your starting running back fumble twice, including once in the end zone. The Redskins had another fumble when center Spencer Long was pushed back into quarterback Kirk Cousins on a third-and-1.

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Suddenly, the Redskins have reached a crucial point in their season. They have tight end Jordan Reed still sidelined with a concussion. Left tackle Trent Williams was hurt late Sunday and cornerback Josh Norman also left with a concussion. Meanwhile, the Redskins have to travel to London on Thursday night. Not a good time.

“We’re still a pretty good team here,” Redskins receiver DeSean Jackson said. “To be in dog fights with teams we feel we should be winning easily is definitely frustrating. We have a lot of good players on this team. We should be winning, not struggling. That’s something we have to figure out as a team.”

But they have a bigger issue with running back Matt Jones and his continued problems with ball security. He fumbled once when not hit -- another concentration lapse -- but recovered. However, he also fumbled into the end zone in the first half when he was around the 2-yard line. After that play, Jones wasn’t much of a factor and finished with just 10 carries for 27 yards. More yards are available, but he’s not consistently getting them. That’s OK if he’s growing, but if he’s not getting those yards and fumbling as well? That’s not going to help.

"It's extremely disappointing, especially when you beat yourself. That's the hardest part to deal with," Redskins left tackle Trent Williams, dealing with a hyperextended left knee, said of the loss.

Kirk Cousins did his part to leading the Redskins on a late surge, but the game really was lost much earlier. Gregory Shamus/Getty Images

Yes, the defense caved late. It let Detroit drive 75 yards in six plays, offering little resistance. It let the Lions win a game the Redskins nearly snatched, dropping them to 4-3 and snapping a four-game winning streak. The defense was playing without Norman, and that made a difference on the last series, but that wasn’t the only reason this one got away.

The defense, for the most part, did a solid job -- good enough to win with more help. The Redskins know what their defense is about; it's an improving and smart group but not one that will just shut a good offense down all game.

The sad part for Washington is that it wasted two terrific series by the offense led by Cousins. He had shown what he needed to, leading what seemed to be a game-winning drive. He delivered with clutch throws and ran the final 19 yards for a score. Cousins has slowly improved this season, and this would have been the sort of game that boosted his confidence.

But this game was lost early. It was Jones’ fumble. It was the fumbled exchange. It was kicker Dustin Hopkins, who usually is automatic, bouncing a 45-yard field goal attempt off the upright for his first miss of less than 50 yards this season.

"If we played like we did in the fourth quarter, the game would have been different," Redskins right guard Brandon Scherff said.

The Redskins want to be taken seriously. One game does not derail their season, but they certainly had a chance to write a different narrative Sunday. There's not much margin for error in the NFL. That's why it's important to take care of business early if you want to win late.