Before the dust settled on college football's opening weekend, Northwestern had already set the tone for the style of play necessary to excel in the Big Ten this season. That day, Northwestern quashed nationally ranked Stanford 16-6, holding the Cardinal to just 240 yards of total offense and their lowest point total since 2007.

Wildcats coach Pat Fitzgerald called it one of the finest defensive performances he had seen from his team in 10 seasons as head coach -- words that have been validated as Stanford has won six consecutive games while scoring no fewer than 31 points to crack the AP top-10.

Defense, of course, has always been a staple of Big Ten football, and it will surely continue into the back end of the regular season when the weather worsens. But in a sport that prides itself on toughness, physicality and winning the line of scrimmage, league teams have taken that mindset to another level defensively this season.

Michigan became the first FBS team to shut out three straight opponents since 1995, when Kansas State accomplished the feat. Wisconsin didn't allow more than three points in three straight games this season for the first time in its program since 1937. Five different teams have pitched shutouts at least once.

Through Week 8, five Big Ten teams rank in the top 20 nationally in both scoring defense and total defense (Michigan, Wisconsin, Iowa, Ohio State and Northwestern). The ACC, with six teams in each category, is the only other league that can make such a claim. The Big Ten also has the top two teams in scoring defense. Michigan is first, allowing 9.3 points per game, while Wisconsin is second at 11.1 points.

"I guess it's all an individual choice," said Iowa coach Kirk Ferentz, whose team ranks 10th in scoring defense and 12th in total defense. "For whatever reason, we seem to have more schools in our conference that value that. There are other parts of the country I think where scoring takes a premium. I can only speak for us. But I can also say that being in this conference for quite some time, I think historically you've seen a lot of good defensive play that's been a trademark of the league."

Fitzgerald and Penn State coach James Franklin credited stout defensive fronts for the Big Ten's dominance. The top two sack men in the country are from the Big Ten, with Penn State defensive end Carl Nassib and Wisconsin linebacker Joe Schobert both vying for All-American honors.

"You always have to start with the players," Ohio State coach Urban Meyer said. "I think there's excellent defensive players in this league. The second (thing) is obviously the coaching. Schematically, each week has got a little different wrinkle.

"I noticed that the last two years. Last year, I really started (to). Every week you're facing a top-10 defense, or a top-15 defense. So, players No. 1 and scheme No. 2."

Wisconsin coach Paul Chryst said viewing conference stats is misleading these days because league teams do not play the same opponents given the unbalanced schedules. Indeed, the Badgers' defense has thrived, but they also do not play any of the toughest teams in the Big Ten East -- Ohio State, Michigan State, Michigan and Penn State. Those four teams are a combined 13-2 in league games.

Still, eight weeks is enough time to make some general observations about the place of Big Ten defenses overall. The league was supposed to demonstrate a level of offensive complexity this year with various schemes that made life tough on defenses. At this stage, however, the success of those offensive schemes remains in question. And the balance of power seems to have shifted to the defense.

Quarterback play, for the most part, has not lived up to preseason hype. Last year, six Big Ten tailbacks averaged at least 100 yards rushing per game. This year, there are currently three. Only one Big Ten team -- Ohio State -- ranks in the top 44 nationally in scoring offense. As a point of reference, three Big Ten teams ranked in the top 20 a year ago in scoring offense (Ohio State, Michigan State and Nebraska), while only two ranked in the top 20 in scoring defense (Penn State and Wisconsin).

Also last season, Big Ten teams collectively averaged 29.7 points per game. This year, that marks stands at 28.3 points.

Why the shift? Continuity at defensive coordinator could play a role in the numbers. Wisconsin defensive coordinator Dave Aranda, who has been with the Badgers for three seasons, was the only assistant coach retained under a new staff this year. Northwestern defensive coordinator Mike Hankwitz has held the post since 2008.

Ohio State co-defensive coordinator Luke Fickell has been with the program in some capacity since 2002. And Phil Parker has served as Iowa's defensive coordinator since 2012, but he was the team's defensive backs coach from 1999 to 2011 under Ferentz. First-year Michigan defensive coordinator D.J. Durkin serves as the only outlier among the Big Ten's top-five defenses nationally.

Regardless of the circumstances, three Big Ten teams -- Ohio State, Michigan State and Iowa -- remain undefeated, with visions of competing in the four-team College Football Playoff. And if they are to get there, they will have to carry an old mantra with them to the finish.

"If you want to be a championship-level team," Ferentz said, "it usually helps to be a good defensive team."