Brown adapted and made an impact as a rookie. After his sophomore season, Jauron was replaced as coach by Lovie Smith, who immediately urged Brown to lose the 30 pounds he had gained two years earlier and return to his college playing weight.
Brown thrived under Smith, playing on a defense that also included Brian Urlacher, Mike Brown, Charles Tillman, Lance Briggs and Tommie Harris. The unit led the Bears to back-to-back NFC North championships in 2005-06 and an appearance in Super Bowl XLI to conclude the 2006 season.
Smith's defense was known for its ability to generate takeaways – and return them for touchdowns. It was a mentality he implemented immediately, making defensive players run, run and run some more in practice.
“It was nonsense back then,” Brown said. “It was like, 'Are you kidding me, it's an incomplete pass, why am I picking it up and acting like it's a fumble? Like, what are you talking about?' And he kept playing around with it, and after a while it becomes a mentality. That's exactly what we do.
“And once you got your body in shape to run non-stop all day long, the defense just took off. That talent was there. It was more or less just a matter of molding that talent and getting it to where he wanted it to be… It didn't.” It took a long time, but it was definitely hard, hard work.