There were a couple concerns in the previous go-round.
Rumors of him free-lancing. As a starter the team relied on him. The 2016 LB depth chart was Hightower, Collins, Shea McClellin, Barkevious Mingo, and rookie Elandon Roberts. There was less depth the team was comfortable with. In this situation he would come back as depth - if he's not with the gameplan, he doesn't play.
Rumors of his bad attitude in the locker room. When he was shipped out of town, players said "we just lost the best player on our defense." As a perceived team leader, his attitude was impactful. He's not going to be in a leadership role. The other defensive starters on that 2016 team included Malcom Brown, Alan Branch, Jabaal Sheard, Rob Ninkovich, Collins, Hightower, Malcolm Butler, Logan Ryan, Devin McCourty and Patrick Chung. Ninkovich, McCourty, and then not a lot of locker room leaders. In this situation he's not coming in as a locker room leader.
At this point in free agency, he's looking to compete for a roster spot. Very little guaranteed money.
At the on-the-line linebacker role, there's Hightower, Van Noy, and Calhoun. Period. One of them gets hurt and you are real thin. At off-the-line you have a recovering Ja'Wham Bentley, Roberts, recovering Christian Sam, and undrafted Terez Hall. So Collins is basically competing with Calhoun for a roster spot. Calhoun has one half sack in his NFL career. Collins is much more athletic.
You'd look at him like Inman. Decent shot to make the team; competing with some undrafted rookies and aging/recovering vets for a roster spot; better play some special teams.
