Time for a turnaround on D

The head coach matters. He does. He is the chief executive officer of an NFL franchise. He is the person ultimately responsible for the team's success. He is the one accountable.

John Fox matters. But when it comes to the Denver Broncos' ultimate success this season, it won't matter which man is the head coach -- or, for that matter, the quarterback -- if the defense doesn't start blocking, tackling and getting to the quarterback better.

In this era, offense sells. But in January and February, defense still wins in the National Football League. That has not changed. And that will continue to be true whether it is Fox or Jack Del Rio or Peyton Manning at the helm of the Broncos.

Over the weekend, Fox had a health scare while playing golf in Charlotte, N.C., during the Broncos' bye week. He needs heart valve replacement surgery. Fox knew his heart was an issue. He was hoping to stave off the surgery until a more convenient time, like after the Broncos made a run to the Super Bowl. Now, it should happen early this week. Fox will be out indefinitely, maybe a few weeks, maybe a few months.

The Broncos have named Del Rio, their defensive coordinator, the interim head coach. Del Rio makes sense. He is a mini-Fox. Defensive coach. Well respected. Has head-coaching experience after nine years as Jacksonville's coach. Is a no-nonsense guy the players respect because he demands effort, expects accountability and makes them better. Del Rio went 73-63 with the Jaguars and made the postseason twice with far less talent than the Broncos have. He knows how to lead a franchise. He knows how to delegate responsibility. But for the Broncos to achieve the success they seek, they will need the defense to improve, to become more than it has shown so far and to reach the quarterback.

The defensive side of the ball is the key to Denver's success. The offensive pyrotechnics are great. Scoring sells. Manning is amazing. But ultimately, it comes down to winning the line of scrimmage and getting off the field and, thus far this season, the Broncos' defense has not been able to do that.

Since the NFL-AFL merger, 16 teams have scored 500 or more points in a season. The Broncos are on pace to become the 17th. Of the previous 16 teams, only four have won the Super Bowl. Three did it by also having a high-powered rushing attack.

The Broncos don't have a top rushing attack. They also don't have a defense that can win them games. Although Denver played better in its pre-bye game against Washington, the wakeup call came in Week 5 against Dallas, when the Broncos gave up 470 passing yards and 48 points to the Cowboys.

Denver's issues have been many. Elite pass-rusher Elvis Dumervil is in Baltimore. Star linebacker Von Miller was suspended for six games. Veteran cornerback Champ Bailey has been injured and played in only two games.

The 11 players the Broncos expected would start on defense have yet to play in a game together this season. That matters, too. The Broncos have 22 sacks this season, tied for 17th in the league, but many have come when opponents have been forced to throw to catch up.

In two weeks, after playing at San Diego in Del Rio's first game as head coach, the Broncos will find themselves in the ultimate philosophical battle against the undefeated Kansas City Chiefs. It will be the Broncos' offense versus the Chiefs' defense. Kansas City is undefeated thanks to a defense that has yet to yield more than 17 points in a game this season.

The late, great Philadelphia defensive coordinator Jim Johnson used to say that if his defense held an opponent to 17 points or fewer, his team should win. Kansas City has done that and is the lone undefeated team in the league.

The Chiefs win ugly and have had the great fortune of playing against some inexperienced quarterbacks, but they win. Defensive touchdowns. Special-teams touchdowns. They don't blow anyone away with their offense, but they move the chains and win games.

Denver has won games, but the Broncos need more from the defensive side of the ball to win in the postseason. As the Broncos emerge from a bye week without their head coach, the question now is: Can they change? Can they evolve? Or are they what they've shown this far: a team that bleeds yards and allows the quarterback time to operate and relies on the offense to blow opponents out?

We will see soon enough. In the next month, Denver will play on the road against San Diego, New England and Kansas City, plus will get the Chiefs at home.

For the Broncos to achieve their goals, they will have to be better defensively. Del Rio certainly knows this. And if not, all he needs to do is watch San Francisco's final offensive series of Super Bowl XLVII, when the 49ers fell 5 yards shy of winning the Vince Lombardi Trophy.

Why? Defense matters.