Once the gold standard in the NFL, the Dallas Cowboys have been the epitome of mediocrity over the last few years. With a win over the defending champion Seattle Seahawks in Week 6, “America’s Team” might finally be returning to its winning ways.

Dallas entered Seattle as one of the biggest underdogs of Week 6, and left with arguably the most impressive win of the 2014 season, and the best record in the NFL. After beating what many experts considered to be the NFL’s top team, the Cowboys are forcing the rest of the league to view them as a potential Super Bowl contender.

It might be difficult for some to group Dallas among the league’s elite teams this early in the season, considering recent history. The Cowboys have missed the playoffs in each of the last four seasons, never finishing with a winning record.

With head coach Jason Garrett and quarterback Tony Romo at the helm, the Cowboys have been a perennial .500 team. Before the start of the season, they had the worst betting odds of any NFC East team to win the division.

Through six games, though, Dallas is proving that 2014 might be different than past seasons. Below are five reasons why the Cowboys could reach the Super Bowl for the first time in 19 years.

DeMarco Murray playing like an MVP

It’s been 21 years since the Cowboys had an MVP winner, but there’s a realistic chance that will change this season. In the race for an award that has traditionally been dominated by quarterbacks, Murray has been one of the leading candidates to be named the best NFL player of 2014.

No other offensive player has dominated his position like Murray this year, out-gaining the next closest runner by 243 rushing yards with 785 yards on the ground. He’s been a workhorse for Dallas, leading the league in carries, and still managing to get nearly 5.0 yards per attempt. Murray has been essential to giving the Cowboys a top five offense, considering they sport an average passing attack.

Murray has been aided by a good offensive line, but he’s been the best playmaker in the league, piling up yards after contact and totaling six rushes of at least 20 yards. Prior to the win over Seattle, Murray ranked third with 5/1 odds of winning the MVP. Against the Seahawks' elite defense, he rushed for 115 yards, and became the first running back since Jim Brown to rush for at least 100 yards through the first six games.

Tony Romo's efficiency

Few NFL players, if any, have undergone more scrutiny than Romo in the last few years. While some of the criticism has been warranted, the quarterback is proving that he might not get the credit that he deserves.

In Week 6, Romo led an 80-yard drive that gave Dallas the lead with just over three minutes remaining. The drive turned out to be Romo’s 26th game-winning drive since 2006, giving him the most of any player in football. If Dallas reaches the playoffs, the team will have a good chance to make a run with the veteran under center. He's excelled in pressure situations this season, giving the Cowboys three comeback victories.

Romo has quietly been one of the most efficient quarterbacks in the league. Since the season opener, which saw the Cowboys lose their only game of 2014, he has thrown 10 touchdown passes and just two interceptions. Despite a poor first game, Romo finds himself with a top five passer rating and completion percentage.

An over-achieving defense

Last year, the bulk of the Cowboys' problems were on defense. The unit was historically bad, allowing a league-worst 415.3 yards per game. After losing linebacker DeMarcus Ware and defensive tackle Jason Hatcher in free agency, the defense was projected to rank near the bottom of the league, once again. The unit, though, has exceeded expectations under new defensive coordinator Rod Marinelli.

Even with Morris Claiborne going down for the year, and Orlando Scandrick missing the first two games with a suspension, the Cowboys are tied for seventh, allowing 21 points per game. Players like Barry Church and Justin Durant have stepped up, leading the team with 64 total tackles, and Dallas hasn’t missed their former Pro Bowlers. Meanwhile, middle linebacker Rolando McClain has been exceptional.

The Cowboys have played their best against their toughest competition, holding Drew Brees and the New Orleans Saints to just 17 points, while forcing MVP candidate Russell Wilson to have his worst game of the season.

Offensive Line creating holes and protecting Romo

A poor offensive line has been one of the main reasons why the Cowboys haven't been in the playoffs since 2009. The unit is currently among of the best in the league, thanks in part to left tackle Tyron Smith, who is enjoying another strong season.

Dallas has used the draft to improve their offensive line, taking center Travis Frederick last year and right guard Zack Martin with the team’s top pick in 2014. The selection of Frederick was highly criticized, and owner Jerry Jones nearly took quarterback Johnny Manziel in May, but the two picks have worked out well for the Cowboys. 

The line has protected Romo, who missed the final game of last year with an injury, as 18 other quarterbacks have been sacked as many or more times than the veteran. While Murray has been terrific, he would not be an MVP candidate without a top offensive line. Even backup running back Joseph Randle has played well, averaging 7.1 yards per carry on his 16 attempts.

Clutch Plays

The Cowboys are often viewed as one of the most talented teams in the NFL, with their failure to execute in key moments keeping them out of the postseason. That couldn’t be further from the truth in 2014, as Dallas has been very clutch, on their way to a 5-1 record.

Two of the Cowboys victories have been of the blowout variety, but they’ve needed to make big plays down the stretch in their other three wins. Late interceptions keyed the team’s wins in Week 3 and Week 6, and the Cowboys made the necessary plays in overtime to beat the Houston Texans in Week 5. Terrance Williams's fantastic 23-yard reception in the fourth quarter on third down and 20 yards was among the NFL's best plays on Sunday.