LAKE FOREST, Ill. -- Vic Fangio weighed several factors before ultimately agreeing to a three-year extension with the Chicago Bears, but the respected defensive coordinator insisted Thursday that he never asked for more control over the direction of Chicago's defense.

Why?

"I mean, [former Bears head coach] John [Fox] basically let me do everything, really, anyway," Fangio said. "I don't see much difference there."

With Fox largely uninvolved with the defense, Fangio and his assistants -- most of whom Fangio expects to retain -- inherited one of the NFL's worst defenses in 2015 and improved the unit significantly over the course of three seasons.

Fangio said he had other employment options following Fox's dismissal, but that he felt good about new head coach Matt Nag's vision for the future.

"I just had to feel comfortable with everything," Fangio said Thursday. "You know, who the head coach was going to be and the continued direction of the team as far as where we were headed, roster-wise.

"It was a drawn-out process in that there were a lot of possibilities available, and so it became a comparison thing, too."

For Nagy, the opportunity to keep Fangio, 59, was too good to pass up.

"To me it was really simple," Nagy said. "The numbers speak for themselves. Here's a guy that has been in this league for a very long time and the production is there, talking about a top-10 defense year in and year out, a guy that me as a head coach will be able to learn [from] defensively, some of the ins and outs of what defenses do so well.

"The biggest thing going into it with Vic was just trying to figure out his philosophy, my philosophy, how it meshes together, can we make it work as people, as peers and as friends, and it was easy to tell right away when we met that that was going to happen. I'm excited to keep him on board and really looking forward to it."