MIAMI GARDENS, Fla. >> A year ago, the Miami Dolphins began December with a loss to San Francisco that jump-started a five-game losing streak.

Sunday’s 45-15 rout of the Washington Commanders was an emphatic turnaround for Miami, which is 9-3 for the first time in 22 years.

“I think it says a lot about where this team has grown from last year,” coach Mike McDaniel said. “What I’ve seen is coaches and players fully commit to the idea of getting better, and it says a lot about the team because everything that you see last week, this week is an accumulation of deliberate intent. And guys are getting better at their craft. Really in all three phases there’s a lot of growth.”

The Dolphins extended their cushion in the AFC East to three games and moved into a tie for the best record in the conference.

It didn’t take long for Tua Tagovailoa and Tyreek Hill to take advantage of the struggling Commanders defense.

Tagovailoa found Hill for a 78-yard touchdown on the Dolphins’ third play of the game, and again for a 60-yard score in the second quarter.

On his first touchdown catch, Hill said Tagovailoa noticed the man coverage with no safety over the top and signaled for Hill to change his route, resulting in Miami’s longest offensive play of the year. Hill leads the league with 1,481 receiving yards and 12 TD catches.

“It’s all film study, mostly,” Hill said, adding that Tagovailoa has the freedom in Miami’s offense to call those types of audibles. “Some teams typically do the same things throughout that season on third down and it was just one of those looks that it was a favorable matchup.”

Commanders coach Ron Rivera, who called Washington’s defensive plays after firing coordinator Jack Del Rio, said he should have given rookie cornerback Jartavius Martin, who was beat on Hill’s 78-yard score, some help over the top. For his part, Hill was surprised by the scheme.

“Those guys are great at what they do and they also get paid, man,” Hill said, “but at some point, it’s like man. I don’t know, man, I just appreciate it, you know. Thanks for not respecting me I guess.”

Hill finished with 157 yards on five catches, his fifth game this season with 150-plus yards receiving. He’s on pace to become the first player to surpass 2,000 yards receiving in a single season.

On defense, the Dolphins limited Washington to 245 total yards — Miami’s fifth straight game holding an opponent under 300 — despite missing two starters in linebacker Jaelan Phillips (season-ending Achilles tendon tear) and safety Jevon Holland (knees).

“Next man up mentality, that’s how we have to go about it,” cornerback Xavien Howard said. “This is a tough game and people go down but the next man up.”

WHAT’S WORKING

Everything. Miami surpassed 400 yards of offense for the sixth time this season and converted seven of 13 third-down attempts. Tagovailoa’s 141.0 passer rating was the second-highest of his career and fourth-best by any quarterback in a road game this season. Linebacker Andrew Van Ginkel intercepted Sam Howell and returned it 33 yards for a touchdown, giving the Dolphins two straight games with a pick-6.

WHAT NEEDS HELP

Not much. The Dolphins needed to better protect the ball after nine turnovers in their previous four games, and they had no turnovers Sunday for the first time since Week 3.

STOCK UP

RB De’Von Achane. The rookie returned after missing five of the past six games with a knee injury and finished with 17 carries, 103 scrimmage yards and two scores. His nine touchdowns this season (seven rushing, two receiving) are the third-most by a rookie in franchise history.

STOCK DOWN

Offensive line. The Dolphins started their eighth line combination of the season and again dealt with injuries when starters Terron Armstead and Rob Hunt went down during the game. Miami allowed just two quarterback hits and no sacks, but depth is a concern.

INJURIES

Armstead left with an ankle injury in the second quarter and did not return. McDaniel said after the game that he was available to return if needed. … Hunt left in the third quarter after aggravating a hamstring injury that he’s been dealing with for several weeks. … LB Jerome Baker injured his knee in the second quarter and did not return.

KEY NUMBER

21 — Consecutive games by Tagovailoa with a touchdown pass, the longest active streak in the NFL.

NEXT STEPS

Miami hosts Tennessee (4-8) on Monday, Dec. 11.