When the defense is good, the Chicago Bears are good.

That has been a common thread throughout their history. It's the foundation and personality of their winning teams – from the Monsters of the Midway of the 1950s, to the 46 Defense of the 1985 season Super Bowl champs to the 2006 team that lost to the Colts and Peyton Manning in the Super Bowl.

This year's Bears are adding a link to that history. The defense has been good again, and so have the Bears – at least through the first eight games.

There is still a half season to play, with a lot left for them to prove. But they're good enough to be in the first place in the NFC North with a 5-3 won-loss record going into Sunday's home game against the struggling Detroit Lions at Soldier Field.

The Bears have gotten to the top with a strong running game led by Jordan Howard and Tarik Cohen, an improving and enterprising young quarterback in Mitchell Trubisky, and – of course – a strong defense.

With only two winning records and one playoff appearance in the last 11 seasons, and four straight last-place finishes in the division, the Bears have been one of the league's surprise teams thus far.

First-year head coach Matt Nagy, who brought with him a reputation for offensive ingenuity as an assistant coach under Andy Reid in Kansas City, doesn't agree with the thought that the Bears might be ahead of schedule with such a rapid climb.

"I think it's been an interesting start of the year, as always for most teams, but we're only halfway through the season," Nagy said in a conference-call interview with the Detroit media. "There is just so much ball left.

"We've won in different ways, and we've lost in different ways. I think we've kind of learned different ways to do it. When you lose, you try to figure out why and how to not let it happen again. When you win, you figure out why and how you can always improve and be better.

"I like where we're at, but we understand we have a long way to go."

Last week's 41-9 road win over the Buffalo Bills was an example of how the Bears have played complementary football.

The offense did not have a productive day, gaining only 11 first downs and 190 yards. But the defense took advantage of the Bills' lack of offensive firepower by never giving them a chance to gain any momentum.

The Bears had four sacks and four turnovers – three interceptions and a fumble recovery. One interception and the fumble recovery were returned for touchdowns.

"Our defense, the first four games of the season they were lights out, and they were playing really well," Nagy said. "And then we hit a little wall there. That's a part of the game. There are going to be inconsistencies, and there are going to be peaks and valleys, and offensively just trying to figure out who we are."

The Bears have been machine-like in producing turnovers. They rank second in interceptions (14), total takeaways (21) and turnover margin (plus 10), and are tied for third with seven fumble recoveries.

They've accomplished that with star linebacker Khalil Mack missing the last two games because of an ankle injury and being limited in the previous two trying to play through the injury.

Nagy indicated there might be some improvement in his condition.

"We're actually going through all that right now," Nagy said. "It's been tough the last couple of weeks for him. It's a day-by-day thing, and darn near hour-by-hour."

The legacy of the franchise as a tough team overall – especially on defense – is one that Nagy embraced. He wants the current players to connect to the old heroes.

"It's a big part of it, and it's a big part of the city," Nagy said of the legacy. "That's an emphasis that I put on from the first day I walked into Halas Hall. We pay respect to it, but we also want to create our own.

"I just think that we're very fortunate to be put in this situation, and I think it's important for all of our players to understand who came before them."