LAKE FOREST, Ill. – It took a while, but Chicago Bears coach Lovie Smith eventually was able to identify a flaw Monday in the team’s 37-6 drubbing of the Seattle Seahawks.

“Devin Hester had a few problems returning punts,” Smith said after the Bears improved Sunday night to 4-0 for the first time since 1991. “If you have a rookie, you’ll go through a game like that. He’ll come back. He’s a good football player.”

And that was Smith’s confirmation that the Bears have shown very few flaws overall in compiling the best record in the NFC.

Defensively, they have been dominant. The 29 points they’ve allowed through four games is even better than their fabled 1985 defense and represents their best defensive start since 1937.

“It’s hard to score points on our defense, especially at Soldier Field,” Smith said.

The Bears have given up 13 points at home, including the only touchdown they’ve yielded defensively. The only other touchdown they’ve given up came from Minnesota’s defense on the road.

Third-year defensive tackle Tommie Harris sacked Seattle quarterback Matt Hasselbeck twice to bring his total to five this season, tops in the league going into Monday night’s game between Green Bay and Philadelphia.

“Tommie Harris is playing at an unbelievable level right now, just dominating football by Tommie,” Smith said. “Tommie was in the Pro Bowl last year for a reason.”