The Patriots pulled off one of the most stunning trades in franchise history Monday, sending Pro Bowl linebacker Jamie Collins to the Cleveland Browns in exchange for a conditional draft pick.

The deal, reportedly for a third-round compensatory choice, was sealed on Halloween but felt more like an April Fools’ joke to many.

Collins is in the final year of his contract and is one of a handful of Patriots due large pay raises in the offseason as free agents.

Fellow linebacker Dont’a Hightower, defensive end Jabaal Sheard, and cornerbacks Malcolm Butler and Logan Ryan are also up after this season.

“In the end, we did what we felt was best for the football team,’’ said coach Bill Belichick during an afternoon appearance on WEEI radio. “There were a lot of things to take into consideration. I’m sure we could bring up a lot of points to talk about, but in the end, that’s really the bottom line.

Asked specifically if Collins’s contract status was the reason for the move, Belichick said, “I think you could bring up a lot of things and they all probably play into the conversation.’’

The coach said he didn’t deal directly with the Browns and that director of player personnel Nick Caserio was the point person.

Belichick said neither the emergence of rookie Elandon Roberts nor the acquisitions of Barkevious Mingo and Kyle Van Noy affected the decision.

“I don’t think that is part of the decision,’’ he said. “It will be impacted by it, but I don’t think what it is about. This is just the player and his situation, the team, and the team’s situation, and what’s best.’’

The coach also addressed reports that the staff is growing frustrated with the defense.

“Look, we’re 7-1,’’ he said. “There’s always things we could do better. Believe me, I’ve been a lot more frustrated than what our record is right now.’’

Tuesday is the trading deadline, and Belichick didn’t close the door on the possibility of another move.

“It’s hard to tell,’’ he said. “Takes two teams to make a deal. Sometimes they come together quickly. Sometimes you talk for a long time and they never happen.

“I think people in the league know that we’re a team that will trade. So, we get calls from teams. We make calls just to see what some situations are or aren’t, but in the end, really, most of my time and energy has gone into the Buffalo game, watching the tape . . . and getting ready for Seattle and planning for the bye week.’’

According to a league source, the Patriots were “having a lot of trouble’’ in negotiations with Collins on a long-term contract. Another league source said the linebacker turned down an offer of $11 million per year.

ESPN reported that Collins was looking for a deal comparable to the six-year, $114.5 million Broncos linebacker Von Miller signed in July. That pact includes $70 million in guaranteed money.

The franchise tag for a linebacker is projected to be around $15 million for 2016.

While his contract situation most surely played a role in the decision to pull the trade trigger, Collins’s recent performances may have been a factor as well. He had seen his playing time reduced.

Long thought of as a three-down defender, Collins played just 48 of a possible 78 snaps (62 percent) in Sunday’s win in Buffalo. That was a marked difference from the norm. Collins played 100 percent of the defensive snaps in Weeks 1-4. He played 83 percent in Week 5, missed Week 6 with a hip injury, and played 89 percent in Week 7.

Against the Bills, Collins was lifted in favor of Roberts, the rookie sixth-rounder, when the Bills brought in beefy fullback Jerome Felton.

The news stunned Patriots fans and even one of Collins’s former teammates, Chandler Jones, whom the Patriots also traded at a time when he was one of the team’s top defensive players.

“Shheeshhh,’’ Jones tweeted.

Collins has 10.5 career sacks, 5 interceptions, 10 forced fumbles, and 180 tackles. The Patriots drafted him out of Southern Mississippi in 2013.

He goes from one of the NFL’s best teams to its worst. Cleveland is the league’s only winless team at 0-8. The Patriots defeated the Browns in Week 5, 33-13.

Michael Lombardi, who until recently was an assistant to the New England coaching staff, was one of the few not floored by the transaction. He fired off a series of tweets, starting with: “Not surprised by the Pats trading Collins. Not been playing well at all they need to get the defense fixed. This will get their attention.’’

Lombardi intimated that Collins did a lot of free-lancing on the field and specifically mentioned a Mike Gillislee run from Sunday.

“Collins on the second play of the game does whatever he wants and Bills gain 28 yards,’’ Lombardi tweeted. “Been happening all year. It was not going to continue.’’

Lombardi also tweeted: “You are either coaching it or allowing it to happen. Belichick decided he was not going to allow it to happen. Collins talented but . . .’’

Browns coach Hue Jackson doesn’t have a problem with Collins sometimes having his own agenda on the field, telling reporters, “He can freelance for me . . . Hey, the way he freelances is OK with me.’’

The Browns should get a compensatory third-round pick for losing Alex Mack last year. So the Patriots would acquire a third-round compensatory pick for Collins in the 2017 draft. Or they get a straight fourth-rounder in 2018 if the Browns don’t have a compensatory pick. Had the Patriots let Collins walk in free agency after this year, they would have received a 2018 compensatory pick (might be a third-rounder, might not be depending on their free agency gains and losses).

So the Patriots got a sure thing, and got compensation for Collins likely a year earlier than they would have.

Jim McBride can be reached at james.mcbride@globe.com. Ben Volin can be reached at ben.volin@globe.com.