Smith suffered the injury on the first series of the Bears' 31-24 win against the Cowboys last Thursday. Kevin Pierre-Louis assumed Smith's place at inside linebacker. After follow-up tests were conduced Friday, the Bears came to the decision they would shut down Smith.
"I really thought you felt him especially here in the last several games really turning it on, really playing fast," Nagy said of Smith. "He’s always had that every play that he gets, every game that he plays, for the rest of his career, he’s only going to get better and better in my opinion.
"I like where he’s at. It’s just unfortunate that it ended like that."
The second-year linebacker Smith posted two tackles on the opening drive last Thursday, bringing his total to 102 tackles over 12 games this season. The Bears drafted Smith eighth overall in 2018, eventually making him a starter at inside linebacker after a contract impasse came to a conclusion.
Smith, 22, quickly established himself as a key part of the Bears' defense. It's why they understand his absence will be significant.
"He will run sideline to sideline," defensive tackle Akiem Hicks said of Smith. "I mean, he just has a pair of wheels on him that just won't stop. That's one of the things that separates him is he can get anywhere you need him to be, whether it's coverage or chasing a running back in the flats. It's pretty impressive."
Pierre-Louis, 28 has played in 68 NFL games over six seasons but started in only one, that coming in 2015 with the Seahawks. He has primarily served as a special-teams player with the Bears. this season.
The Bears are awaiting progress from inside linebacker Danny Trevathan, who suffered an elbow injury on Nov. 10. Trevathan has not reached a point where a return to action is in consideration. However, the team did not place him on injured reserve with the hopes he could eventually rejoin a playoff push.
Now, the loss of Smith takes away from the identity of this Bears defense.
"You could see the relationships he had with those guys," Nagy said. "You could see Danny Trevathan really take him under his wing. That was very important. He’s a guy that’s really been growing.
"I really am excited with our future with him and just got to get him back on track now health-wise."