Roy Helu‘s leaping 28-yard touchdown run in the fourth quarter was his most memorable play of the day, but his 162 rushing and receiving yards opened up the entire Redskins offense. (Elaine Thompson/Associated Press)

When the Washington Redskins took the opening kickoff of Sunday’s game at Seattle and marched directly down the field — 14 plays, 80 yards, a touchdown — they looked as if they had been an efficient offensive juggernaut all season. There was no sign that, not a month earlier, they endured a three-week period in which they produced all of one touchdown. The running game burst to life behind rookie Roy Helu. The passing game looked crisp with Rex Grossman behind center.

Alas, that drive — not to mention the 416 total yards the Redskins rang up in a 23-17 victory over the Seahawks — are anomalies in what has been, largely, an abysmal offensive season for Washington. The question that arises is simple: What was the difference?

“Any offense, if you want to have balance and the chance for a big play, you’ve got to have a good, solid running game, and that sets up the play-action pass,” Coach Mike Shanahan said Monday, the day after his personal-worst six-game losing streak had ended. “I thought that’s what we were able to do [Sunday]. Our running game was solid against a very good defensive team [and] kind of gave us some opportunities with some play-action passes to come up with the big plays.”

Start, then, on the ground. Helu, a fourth-round pick from Nebraska, turned his first opportunity to play on all three downs into a career day. He gained 108 yards on 23 carries, including a game-changing 28-yard touchdown run in the fourth quarter on which he memorably leapt over a defender.

That not only earned him a third start in the upcoming game against the New York Jets, according to Shanahan on Monday, but it helped establish the entire flow for the offense. In the Redskins’ four wins, they average 138 yards rushing. In their seven losses, that number plummets to 56.9.

“That’s one of the reasons why I believe in the running game through the years,” Shanahan said. “That usually dictates wins, by [being] able to run the football, come up with the big plays in play-action. Your third downs aren’t as long, you’re controlling the time of possession, keeping the opposition off the field — different things that lead to winning.”

The rare presence of the running game — the Redskins still rank next-to-last in the NFL in yards per game on the ground — also allowed Washington to control the clock, even as they allowed scoring opportunities to slip away. The Redskins held the ball for 33 minutes 20 seconds against Seattle. Coincidence or not, they’re now 4-0 in games in which they win the time of possession battle, 0-7 when the opponent has the ball longer.

“Normally if you win games, you’re controlling the ball in the fourth quarter, and you’re running the football,” Shanahan said. “. . . When you’re behind, you’re throwing the ball every down.”

In order for the Redskins to get in a situation in which they could control the clock, they needed the lead. They grabbed it in a manner they also have not shown much this season, with a pair of quick strikes. Shanahan’s running game is predicated not just on wearing opponents down through repeated attempts, but by then busting out for a long gain. Until Helu broke free with just under 10 minutes remaining to cut the Seahawks’ lead to 17-14, that big play had been completely absent. Helu’s 28-yard run was Washington’s second-longest of the year, trailing only a 39-yard burst by Ryan Torain in Week 4 against St. Louis.

The play on which the Redskins took the lead was their longest of the season, a 50-yard touchdown pass from Grossman to wide receiver Anthony Armstrong. Only three teams entered Sunday without a pass play of at least 50 yards, and the heave showed Grossman’s ability — and willingness — to go downfield.

In eight starts by Grossman this season, the Redskins have averaged 339 yards of offense and gone 4-4. In three starts by John Beck, they averaged 278 yards and went 0-3. So up pops another question. Does Shanahan regret benching Grossman in Week 7?

“That’s part of trying to figure out who your football team is, especially when you have some missing pieces,” Shanahan said. “. . . You’re always trying to come up with that chemistry and what gives you the best chance to win. That’s an ongoing process.”

Establishing consistency on offense is also an ongoing process. But after the Redskins’ first win in nearly two months, there also is another element that has been missing most of that time: Hope.

“Hopefully, we’ll have a lot of games like this in the future, where you’re moving the football,” Shanahan said. “. . . When you do move the ball like we did, you feel a little bit better about everything — your running game, your protection, your play-action game, your dropback game.

“Everybody’s a lot more positive. To move the ball like we did, it’s a big boost to our offensive players, because they know we have those capabilities. We just need to do it on a consistent basis.”