The Indianapolis Colts continued their recent hot streak with an impressive 23-0 win over the Dallas Cowboys at Lucas Oil Stadium on Sunday.   

It was the Cowboys' first shutout loss since 2003.   

Coming into Week 15, the Colts were among a group of four teams with 7-6 records fighting for the final wild-card spot in the AFC. They are trending in the right direction with seven wins in their last eight games, including back-to-back victories over division leaders in the Cowboys and Houston Texans. 

Andrew Luck didn't throw a touchdown for the second time in three games, but he was an efficient 16-of-27 for 192 yards against a good Dallas defense.

Marlon Mack did most of the heavy lifting for the Indianapolis offense. The second-year running back finished with a season-high 139 yards and two touchdowns on 27 carries. 

Dallas once again had problems on offense with just 292 yards. Dak Prescott went 24-of-39 for 206 yards and one interception. Ezekiel Elliott was held to 87 yards on 18 carries.

Underrated Defense Makes Colts AFC Dark Horse

With so much focus understandably on Luck and the Colts offense during their second-half hot streak, it's been easy to overlook how important their defense has been. 

After giving up 180 points through the first six games, Indianapolis has allowed an average of 15 points per game since Week 7. Some of that may be a function of competition; the Buffalo Bills, Jacksonville Jaguars and Miami Dolphins aren't exactly running opponents off the field. 

The Cowboys offense had a chance to make the Colts pay, yet the team was unable to finish its drives. Dallas held the ball for 19 minutes through two quarters and was trailing 10-0 at intermission. 

One reason for the Colts' defensive turnaround is their ability to get after the opposing quarterback:

General manager Chris Ballard and his staff put together arguably the best draft class in 2018. Second-round pick Darius Leonard entered Week 15 leading the NFL with 135 combined tackles and 90 total tackles and second on the Colts with seven sacks. 

The Colts also have first-year defensive ends Kemoko Turay and Tyquan Lewis to build around (Lewis had two sacks in the first half). 

Entering Week 15, the top two seeds in the AFC were the Kansas City Chiefs and New England Patriots. The quarterbacks of those teams are Patrick Mahomes and Tom Brady, so it will take a herculean effort to slow down either one. 

But Indianapolis is proving it has the ability to turn things on:

Luck has the ability to carry the Colts into the playoffs. He did it from 2012-14 with a mediocre roster, including an appearance in the AFC Championship Game after the 2014 season. 

On Sunday, Indianapolis showed its defense can hold up while waiting for Luck and the offense to get going. This well-rounded roster makes the team a dark-horse contender to reach the Super Bowl. 

Dak Must Lift Cowboys Offense to Ease Burden on Zeke

What kind of quarterback is Prescott?

The answer to this question will determine how far the Cowboys are able to go if they reach the postseason. 

Prior to Week 15, Prescott had been playing the best football of his career over the last eight games:

The Colts were able to make the Dallas offense look a lot like the group from the season's first half, when the Cowboys were 3-5 and averaging 19.3 points per game. Dallas had chances to come away with at least three field goals on each of its first three drives:

Elliott did everything in his power to get the Cowboys into the end zone with 13 carries for 71 yards on those drives. Indianapolis got an easy read on a 4th-and-1 to stuff Elliott and force a turnover. 

Prescott doesn't deserve the blame for all of those drives. Fullback Jamize Olawale dropped a wide-open pass on the play prior to Elliott's failed fourth-down run. 

As the game went on, though, the Cowboys needed Prescott to carry their offense if they were going to make a comeback. 

Instead, this performance was another indication of how reliant Dallas is on Elliott. It shouldn't be overlooked how much offensive coordinator Scott Linehan turned to his running back over the past eight weeks.

Elliott averaged 31 touches per contest during the Cowboys' five-game winning streak compared to 22.3 in the previous eight games. 

The offense hasn't looked good for the past three games, including Sunday's loss. It only scored 13 points against the New Orleans Saints and had nine points through three quarters against the Philadelphia Eagles before the shutout against the Colts. 

As talented as the Cowboys are on defense, Prescott has to make sure opponents respect his ability to throw the ball and ease the pressure on Elliott. 

What's Next?

The Cowboys will host the Tampa Bay Buccaneers next Sunday at AT&T Stadium in their final home game of the regular season. The Colts will play their final home game on the same day against the New York Giants.