Bears defense a litmus test for Nick Mullens

Of everything that has been salvaged from the San Francisco 49ers' 2018 season, the emergence of Nick Mullens is the most unexpected and the most valuable.

Since being pressed into service by injuries to Jimmy Garoppolo and C.J. Beathard, Mullens has surpassed all expectations and heads into the Niners' Week 16 tilt with the Chicago Bears with a 3-3 record having helped orchestrate a late-season surge that has seen them claim wins over the Denver Broncos and Seattle Seahawks.

Mullens leads the NFL in passing yards since Week 13 and has racked up the fourth-most yards across a quarterback's first six games since the merger. Completing 64.5 percent of his passes, Mullens has also been an efficient quarterback and averages over a yard more per attempt than Beathard has done during his 10 starts, according to David Lombardi of The Athletic.

His numbers are those of a quarterback completely at home in his offensive system, and his development in Kyle Shanahan's scheme has been obvious as he and the Niners have knocked off a pair of playoff-contending teams.

As Ted Nguyen of The Athletic wrote in his recent film comparison of Beathard and Mullens, the former Southern Miss Golden Eagle has done a much better job of diagnosing blitzes, moving in the pocket to negate pressure and throwing with anticipation. He also demonstrated an increased aptitude for throwing downfield with touch.

All of these abilities have enabled Mullens to have success against a Denver defense that was fourth in Football Outsiders DVOA through 15 weeks and a Seattle unit that did an excellent job generating pressure against the interior of San Francisco's offensive line.

However, he will face a different level of challenge against the Bears, who rank first in Football Outsiders overall defense DVOA, pass defense DVOA, run defense DVOA, interceptions and takeaways per drive, per Lombardi. Chicago is also fourth in sacks and second in yards per play allowed.

With the best edge rusher in the game in Khalil Mack, supported ably by Leonard Floyd, supreme amounts of interior talent in the form of Akiem Hicks and Eddie Goldman, an athletic and instinctive linebacker in Roquan Smith and an emerging star at cornerback in Kyle Fuller, who has seven interceptions on the season, the Bears have a plethora of ways to make life extremely difficult for Mullens.

As he nears the end of what has been a life-changing season for Mullens, he now faces a litmus test that will help determine just how good he is. Through his displays, the Niners know they have a capable backup who can win games against playoff contending teams, how he performs against the Bears may decide whether other teams in the market for a trade view him as a starter.