The Bears’ ILB tandem of veteran Danny Trevathan and rookie Roquan Smith became the ideal mix of old and new.

After having missed 11 games in his first two seasons with the Bears, the 28-year-old Trevathan started all 16 games in 2018, when he was healthier than he had been since he started 15 games in 2015, his last season with the Broncos. He was second on the team with 102 tackles, trailing only team leader Smith, who had 122, and providing strong veteran leadership on the field and in the lockerroom.

Smith started slowly, feeling his way through the first month, although he had a sack against the Packers on his first snap as an NFL player. The eighth overall draft pick missed all of training camp in a contract dispute and then suffered the obligatory hamstring injury when he returned, which kept him out of the preseason.

But as he became more comfortable in the scheme, Smith seemed to get better every week, showing excellent range as a run defender, even as he sometimes struggled in coverage despite exceptional speed and quickness. Smith also showed a knack for blitzing, finishing third on the team with five sacks in limited opportunities.

“It was huge to watch him flourish, especially in the late part of the year,” Bears G.M. Ryan Pace said. “You talk to Roquan, and you can just feel him getting comfortable in the defense. Now he's not thinking as much, he's just playing with his instincts, and he's playing fast, and those are his greatest strengths, his instincts and his speed. So the sky's the limit for him. It's just exciting to see him grow. And I think you saw a glimpse of what he's going to be, especially in the later part of the season.”

Though he may appear undersized on paper, the 6-foot-1, 236-pound Smith hits with the authority of a much bigger man and impressed his older teammates and the defensive staff with his willingness to accept coaching.

The top ILB backup, 2016 fourth-round draft pick Nick Kwiatkoski, started the opener before giving way to the more athletic Smith, and his playing time on defense was minimal since the two starters enjoyed excellent health. The West Virginia product is an effective run-down player but has limitations in coverage, although he emerged as one of the Bears’ top special-teams performers, finishing third with five tackles.

Rookie fourth-round draft pick Joel Iyiegbuniwe rarely saw the field on defense, but he, too, was a key contributor on special teams, tying for the team lead with six tackles. Undersized at 6-foot-1 and 230 pounds, Iyiegbuniwe has the speed and cover skills to be a factor in sub packages going forward.

MVP: Trevathan.

Most improved: Smith.

Best play: With the Bears clinging to a 14-9 lead and trying to avert an upset bid by the 49ers in Santa Clara, Cal., in Week 16, Trevathan saved the day. Midway through the fourth quarter, the 49ers had driven to the Bears’ 20-yard line when Trevathan notched his second pick of the season. He hauled in a Nick Mullens pass that deflected off the hands of QR Marquise Goodwin, and the Bears hung on for the victory.

Key stat: Roquan Smith’s 122 tackles were the second most ever by a Bears rookie, trailing by only two the 124 tackles that MLB Brian Urlacher had in 2000.

Room for improvement: With Trevathan’s contract up after the 2019 season, the Bears should be contemplating his successor.

2018 Bears position-by-position superlatives:

QBs: Trubisky's developent answered Bears' biggest question

RBs: Chicago Bears ran often, just not very well

WRs: Robinson looks like go-to guy; Gabriel, Miller also emerge as key contributors

TEs: Burton has career year but wait continues for Shaheen to reach potential

OL: Quick decision on Massie a big step toward ensuring 2019 continuity

DL: Bears' defensive success began up front

OLBs: Mack was the star, but not Chicago's only impact edge defender