Thursday marked Day One of linebacker Jamie Collins Sr.'s second stint in New England. Collins broke into the league as a second-round pick of the Pats in 2013 but was shipped to Cleveland in 2016.

FOXBORO – The end of his first stint in New England, he says, was strictly business.

“I don’t know if it worked out or not,” linebacker Jamie Collins Sr. said following the Patriots’ first training camp practice on the fields behind Gillette Stadium. “That’s just the league. That’s the business. You just keep doing what you’re doing, keep working and keep moving forward.”

A second-round pick (52nd) of the Patriots in the 2013 NFL Draft, by 2015 the Southern Mississippi product had earned Pro Bowl status, piling up 115 tackles, forcing four fumbles, recovering two fumbles and intercepting two passes as well that season.

By October of the following year, though, Collins was a Brown, shipped to Cleveland at midseason in exchange for a third-round draft choice in 2017.

“Undisciplined” was the knock against the 6-foot-3, 255-pounder in New England; although physically gifted, he was prone to doing far too much freelancing in the Patriots scheme, it was said.

After 2-1/2 seasons in Cleveland, Collins, who received a four-year, $50 million contract from the Browns following the 2016 campaign, is back.

Released by the up-and-coming Browns, who chose to end their relationship with him on March 6, just two years into that megabucks deals, Collins returned to the Patriots as a free agent on May 16, signing a one-year free-agent deal with the team.

In a talented linebacking corps it’s believed that Dont’a Hightower, a teammate of his then and now, might benefit most from Collins’ return, the latter’s presence freeing the eight-year Patriots veteran to rush the passer from the outside more.

“He’s out here, he’s doing his thing, he’s communicating and he’s making the calls,” Hightower said following Thursday’s practice. “It feels good to have him back.”

As for Collins, he says he’s not looking ahead to what the future may hold for him. He’s too busy, he said, keeping his head down.

“We just come out here and work and do what we’ve got to do,” said Collins. “It’s Day One. So we don’t know who’s going to be where and what’s going to be what. So we just come out here and go to work every day. I come out here, I have my head down and I’m working. I look up at the finish line.”

This camp marks a fresh start, though; or perhaps, in Collins’ case, a fresh re-start, if you will.

“Camp is camp, man,” he said. “They're all hard, no matter how many times you do it. Honestly, every camp is new and it's different. So it’s just a grind to getting your mind right, coming out here and getting it done.”

Collins did commit himself to saying he’s “very happy” to be back in Foxboro where he earned a ring with the 2014 team, closing out that season by totaling a team-high eight tackles in the Patriots’ 28-24 win over Seattle in Super Bowl XLIX.

"I’m very excited,” he said. “It’s another day. It’s our job, it’s my job, so what it is here, whatever my job is, I have a great opportunity to be back in a position to do your job and what you’re really good at. I’m very happy to be back.”