Biggest offseason developments: The Bears parted with veterans Pernell McPhee and Willie Young and let Lamarr Houston go into free agency. They re-signed Sam Acho to a two-year, $5.5 million contract, signed former 49er Aaron Lynch to a one-year, $4 million contract and added Kasim Edebali as depth after a June tryout. While many thought edge rusher to be one of the Bears’ greatest offseason priorities, they waited until the sixth round to draft one, Utah’s Kylie Fitts.

Currently on roster:8.

Projected on final roster: 4-5.

Roster locks: Leonard Floyd, Sam Acho.

On the bubble: Aaron Lynch, Isaiah Irving, Kylie Fitts, Kasim Edebali.

Practice-squad

candidates: Andrew Trumbetti, Elijah Norris.

What to like:Outside linebacker feels like one of the more precarious position groups, mostly because the Bears appear to be banking on a lot to go right.

McPhee, Young and Houston combined for 10 sacks in 2017 and provided leadership that will fall to Acho and even Leonard Floyd in his third season.

Acho returns after a season in which he had 45 tackles, three sacks and was a strong part of the run defense. He is the only player in the group without a bunch of question marks.

Few defensive issues feel as important as the health of Floyd, who had surgery on his right knee in 2017 to repair his medial collateral and posterior cruciate ligaments. He wore a brace while practicing this spring and said in June he expects to be full go by training camp.

Lynch is a wild card, a player who once excelled under defensive coordinator Vic Fangio but has battled injuries, weight issues and a suspension since. The Bears would love if Isaiah Irving capitalized on the lack of depth and put together a breakout second season. Fitts has to leave behind the health concerns that disrupted his college career.

Fangio said the Bears hope they can get the pass rush they need from the current group.

“Leonard, when he’s been healthy, has proven to be proficient enough,” Fangio said. “Lynch, he’s had a checkered career to say the least, but there has been some display of talent throughout his career at times. Hopefully we can get that to be more consistent. Sam Acho made some improvements last year in that area. We’ll see how Isaiah and these young guys come along.”

Biggest question: How quickly can Floyd get back to where he was before his knee injury?

The 2016 first-round pick enters 2018 with 67 tackles, 11 1/2 sacks, two safeties, four passes defended and a forced fumble in 22 games. But Fangio conceded this spring that the missed time after Floyd’s injury has hindered his development.

“It has — there’s no way around that,” Fangio said. “Everybody needs as many reps in practice as they can get. He’s really anxious to do it. He’s been begging the trainers and medical people to let him out there a little earlier. But I think he’ll overcome it.”

Floyd said he is ready to do his part on and off the field.

“Everything that comes with it,” he said, “being accountable, knowing your playbook and going out and showing that I’m a leader and practicing like a leader.”

Fresh face:Fitts said this spring the injuries that wiped out most of his 2016 season and limited him in 2017 at Utah were “just a run of bad luck, and it’s over now.”

He needs to return to his 2015 form, when he had seven sacks and four forced fumbles. Fangio said this spring it was too soon to tell what Fitts can be.

You should know:Lynch had 12 1/2 sacks in his first two seasons with the 49ers and 2 1/2 over the last two years. One reason he and the Bears think this could be a fit is his prior relationship with Fangio, but he has to stay healthy. He was slowed this spring by ankle and hamstring injuries.

Big number: 10 — Games Floyd missed the last two seasons.

ckane@chicagotribune.com

Twitter @ChiTribKane