The Chicago Bears are a franchise historically known for stout defense and opportunistic offense.

Thanks to former head coach Marc Trestman and GM Phil Emery, they've had neither in recent seasons.

With Trestman and Emery off to the Land of Misfit NFL Coaches and John Fox and Ryan Pace the latest men tabbed to bring the Bears to ultimate glory, the return to a proud, difficult-to-play-against organization can hopefully begin again.

With the NFL free agency period mostly behind us, the 2015 NFL Draft becomes our first real glimpse into the type of building blocks Fox and Pace will target to help them in the arduous process of rebuilding the Bears in their ideal image.

"With their defense having collapsed to 25th and then 28th in DVOA over the past two seasons, the Bears needed to find new defensive pieces whose jerseys hadn't been burned, either on the field by opposing receivers or in effigy in the parking lot. New general manager Ryan Pace took steps in that direction by adding Pernell McPhee, Mason Foster, and Antrel Rolle during free agency," writes Bill Barnwell of Grantland.

The additions of McPhee, Foster and Rolle indicate Fox and Pace's focus this offseason will likely be fixing a defense which seemed wholly incapable of containing even the most ineffective offensive attack by season's end.

Will the 2015 NFL Draft provide further reinforcements?

"He inherits a pair of relatively high 2014 picks in second-rounder Ego Ferguson and third-rounder Will Sutton, but the Bears are otherwise relying on veteran question marks like Jay Ratliff and Ray McDonald. USC's Leonard Williams won't be waiting at no. 7, but the Bears could be in the running for 5-technique Oregon end Arik Armstead or 339-pound Washington nose tackle Danny Shelton."

Shelton is likely to go somewhere in the vicinity of the top-10 - he's a big, disruptive tackle with good burst who excels against the run. By most accounts he's intelligent, a hard worker and has the capability to collapse the pocket. He could potentially slot in immediately as the starting nose tackle in new Bears defensive coordinator Vic Fangio's 3-4.

While a pass-rusher might be a sexier selection at No. 7, a good defense is built off building-blocks like Shelton who can anchor a defense and a line for the next decade.

Armstead, on the other hand, is a player whose draft value is difficult to gauge with any certainty. He's got the measurables of a high first-round pick, but the production of a mid-round prospect.

"I see the power in his hands and all of his tools, but I don't see the production or the consistent push that I feel like I should see from him. He could end up being a monster, but you have to understand that what you get right now is just a big athlete with some upside," a Pac-12 area scout told NFL.com. 

Then again, Armstead played almost exclusively at 3-4 defensive end at Oregon - a position known mostly for eating up blocks so that other players can flow to the ball unencumbered - and may be best suited for that position in the NFL.

Armstead seems likely at this point to be available early in the second-round and, along with Shelton, could help Fangio, Fox and Pace immensely as defensive building blocks in the oftentimes difficult transition to a 3-4.