The Indianapolis Colts are off to a 3-1 start thanks in large part due to their defense.

Indy's defensive unit ranks first in the NFL in terms of points and total yards against, and the Colts are coming off a dominant defensive performance against the Chicago Bears in Week 4.

The numbers would seem to indicate the Colts have had the best defense in the league early on. Defense end Justin Houston agrees:

“We really believe we’re the best defense playing this game right now,” Houston said, via Mike Wells of ESPN.

Addressing the defense was certainly a priority for Colts general manager Ryan Ballard in the offseason.

Indianapolis had the No. 13 overall pick in the 2020 NFL Draft, but instead chose to trade the pick to the San Francisco 49ers in exchange for former Pro Bowl defensive tackle DeForest Buckner.

The move has paid major dividends early, as Buckner has been a run-stuffer while also racking up 1.5 sacks and a team-high eight quarterback hits.

Houston has played a major role, as well. The former All-Pro has 3.5 sacks, four tackles for a loss and five quarterback hits, posing as Indy's most formidable pass rusher on the edge.

The advanced metrics also tab the Colts as having the best defense in football. Indianapolis ranks first in defense-adjusted value over average (DVOA), per Football Outsiders.

Granted, the Colts have not faced the most imposing of offenses. Their last two games have come against the New York Jets and Bears, respectively. That said, they totally shut down Kirk Cousins and the Minnesota Vikings in Week 2, and you can only play the next opponent on the calendar.

The Colts brought in veteran quarterback Philip Rivers to be the potential difference-maker under center, but it is the defense that could help the Colts compete for an AFC South title.