DAVIE, Fla. -- The biggest upgrade for the Miami Dolphins since the Bill Parcells regime took over has come in December.
For years, the franchise's fortunes tended to sink with the temperature. But the Dolphins are 6-0 in December under coach Tony Sparano, and a pair of wins this month have them above .500 for the first time in 2009.
In two weeks, the Dolphins (7-6) have gone from playoff long shots to serious contenders. They're tied with three other teams for the sixth-best record in AFC -- six make the postseason -- and they can still overtake New England (8-5) for the AFC East title.
"You have to play your best ball in December," defensive end Randy Starks said Monday, "and right now that's what we're doing."
The Dolphins may need a sweep of their final three games to reach the postseason, but their remaining opponents all have losing records. Miami plays Sunday at Tennessee (6-7).
"We need to win the rest of our games," Starks said. "If we don't, it doesn't matter who beats who. We know one loss would put us out of it."
The Dolphins have become good at surging down the stretch. Before Sparano took over in 2008, they had a winning December only twice in the previous 11 years. But last season they swept all four December games en route to their first playoff berth since 2001.
Now the Dolphins are mounting another late charge after starting 0-3. They rallied to beat New England on Dec. 6 and won Sunday at Jacksonville 14-10.
What's the secret? Sparano said he encourages a strong work ethic in his players by stressing the need to improve from September to December. While that's the goal in every NFL city, it doesn't always happen.
"During the course of a long season, some teams can get worse," Sparano said. "When I say work ethic, I mean going out there every day getting hit over the head with the same baseball bat but getting something out of it. These guys do a pretty good job of understanding how the details matter. With that in mind, you continue to get better at some of the little things that help you win games in December."
Little things help win close games, too, and Sparano's team has won six in a row decided by seven points or less.
Improvement is widespread. The Dolphins have given up 134 points in the fourth quarter, a one-season franchise record, but in the past two games they pitched shutouts in the final period. Sparano said the secondary, offensive line, receiving corps and kick-coverage units are all significantly better than at the start of the season.
"I see a lot of improvement in a lot of places," Sparano said.
The Dolphins are hardly juggernauts. They rank 18th in the league in both offense and defense. Opponents have outgained Miami by nearly a yard per play, and no playoff contender has a worse takeaway-giveaway margin than the Dolphins' minus-five.
But thanks to a strong ground attack and the NFL's second-best conversion rate on third down, Miami averages a five-minute advantage per game in time of possession.
"One of the thing we talked about the first day we got here was, `We've got to get good at something. We've got to be able to hang our hat on something," Sparano said. "I'm not saying we're good at many things right now. There are a lot of things I'd like to be a lot better at. But there are some things we're good at."
On Sunday, the Dolphins again relied heavily on 32-year-old Ricky Williams, who topped 100 yards rushing for the fourth time in the past five games. They held to Maurice Jones-Drew to 59 yards and forced the Jaguars into seven three-and-outs. And they benefited from another solid effort by Chad Henne, who set a team record with 17 consecutive completions and improved to 7-3 as a starter.
As a result, Miami won despite failing to score in the final 38 minutes and finishing with three turnovers to none for Jacksonville.
"We've been fighting all year to get over .500 and string back-to-back games together," Williams said. "We're starting to do that by finding ways to win even when we make mistakes."