GLENDALE, Ariz. — All through the winning streak, through the soaring rise from the empty start to the top of the NFC East, there always has been this lingering sense that the Washington Football Team’s dreams for 2020 were only going to be as strong as the surgically rebuilt right leg of quarterback Alex Smith.

And suddenly Sunday those fears became real in an anxious montage of disastrous images: Smith tripping over a teammate’s foot . . . Smith hobbling on the sideline . . . Smith’s leg being wrapped by the trainers . . . Smith walking slowly to the locker room just before halftime . . . Smith limping back as the second-half kickoff soared toward the closed roof of State Farm Stadium.

The fourth win of Washington’s improbable streak probably will be remembered for Chase Young and the fumble he picked up and ran back for a touchdown, and for a defense that took an interception back for a touchdown, had four sacks and tormented the San Francisco 49ers in a 23-15 victory. But, more importantly, it was the day Washington found out a little more about Dwayne Haskins and realized that perhaps it can withstand the disaster that would come with losing Smith.

In the oddest game of the strangest season, Haskins pulled on his helmet and ran on the field for the first time since he was benched and banished to third string after the season’s fourth game and played well enough to help Washington win. It was not a spectacular performance. He threw behind a couple of receivers, almost had one throw intercepted and attempted a few sidearm tosses that didn’t work.

But he also managed the game, much the way Smith, whose injury does not appear to be serious enough to keep him out of next week’s game against Seattle, has managed games. And on Sunday, that’s what Washington needed: a game manager who kept the team moving just enough to let the clock wind down.

“He’s showing growth, and that’s what we’re going to continue to look for,” Washington Coach Ron Rivera said in his postgame video conference.

“Good decisions,” Rivera later said when asked what growth he had seen from Haskins. “Quick decisions. Some poise back there.”

None of the Washington coaches ever have doubted Haskins’s talent. “There’s very few people who can throw the ball like that. He’s in a select group that way,” quarterbacks coach Ken Zampese recently said of Haskins. “But there’s more to quarterback than that, and we’re working on that now,” Zampese continued.

Over the past few weeks, Haskins has been besieged by his coaches and teammates to understand that he must be able to do so much more than just throw an impressive deep ball if he is going to play in the NFL. Slowly, he started to understand their pleas. He arrived early to the practice facility and stayed late, asked more questions and studied opponents more than in the past. Watching Smith prepare for games these past few weeks has given him a new understanding, he said after Sunday’s victory.

Still, the question of how Haskins would handle his second chance dangled inside the empty stadium as the second half started. On Washington’s sideline, Smith walked slow 15-yard circles behind the kicker’s net, clutching his helmet, trying to loosen up what Rivera described after the game as a strained calf. Smith hobbled slowly, gingerly moving his feet from the edge of the grass to the black path that separated the field from the stands. He looked uncertain, afraid to move faster, as if doing so caused him to hurt himself even more.

On the field, Haskins looked more confident than he had before. It was the worst situation for a quarterback to step into, coming in cold against one of the NFL’s best pass defenses. Washington held a precarious 13-7 lead. But slowly it moved downfield. He hit J.D. McKissic with a 13-yard pass that got Washington deep into San Francisco territory. The drive took almost 5 minutes off the clock and led to a field goal that made the score 16-7.

It seemed as if everyone on Washington’s sideline felt hope. By the end of the third quarter, Smith had placed his helmet on the top of an equipment box and sat on the bench. There was no need for him to try to play.

Perhaps it says something about this team and this season that Haskins completing 7 of 12 passes for 51 yards was seen as a success for Washington. And yet the coaches weren’t asking him to throw for 150 yards. Smith had struggled to complete any of his passes before the injury and had just 57 yards himself. This was always going to have to be a defensive victory, won with big plays from an increasingly dominant front and supported offensively by quarterbacks who did enough to eat up time.

“I’m proud to be here right now,” Haskins later said as he sat in a room beneath the stands, talking into a video conference camera. He called the last few weeks the “biggest adversity” of his life. His voice wavered and caught as he spoke. He said he had tears in his eyes as he walked off the field at game’s end. He said he had spent the previous two months wondering whether he would ever step onto the field in a game again.

He said this not knowing whether he will get that chance again for Washington. Rivera acted in his postgame news conference as if Smith will be able to play against Seattle next week. The way Smith has moved Washington through its winning streak suggests he has a chance to be the team’s quarterback again next season — if his legs hold up.

On Sunday, when one of those legs failed, Dwayne Haskins at least gave Washington something to think about when considering that still uncertain future.