Marks said the decision was made after Irving had visited with a specialist the past few days.
"He's obviously upset about this, and we are here to support him, support the process moving forward with him and the rehabilitation," Marks said before the Nets' game against the Philadelphia 76ers at Wells Fargo Center. "He saw specialists including our people at [New York's Hospital for Special Surgery] and it has been a group consensus that at this point in time, and this juncture, this is the best course of action."
Irving, who joined the Nets as a free agent last summer alongside Kevin Durant, played in just 20 games in his first season in Brooklyn. He missed 26 games over the span of nearly two months with a right shoulder impingement, before eventually returning in mid-January following a cortisone shot.
But after he missed the final five games before the All-Star break with a knee sprain he suffered in a nasty-looking fall in a loss to the Washington Wizards on Feb. 1, it was determined that it wasn't worth Irving playing through pain in the shoulder any longer, and that surgery was the right course of action.
What wasn't on the table, Marks said, was Irving getting another cortisone shot.
"I think we look at our players' long-term health as the No. 1 priority," Marks said. "Kyrie has been adamant like the rest of us that he would take one cortisone shot and see how it goes.
"We are looking at the big picture here. We are not looking at the next 2-3 months. We are looking at the next 2-3 years."
The possibility for surgery had been on the table during Irving's initial absence. At the time, it was decided that the better path was for Irving to get the cortisone shot and see how his shoulder responded, in the hopes of avoiding surgery altogether.
"A cortisone shot lasts as long as it can," Irving told reporters back on Jan. 4. "You either continue to get cortisone shots, which is obviously detrimental to your health and your muscles, or you go get arthroscopic surgery. For me, it's just about being able to go back out there after the right amount of rehab, the right amount of rest and recovery and see what we can do for the rest of the season and then reevaluate after a few months."
It turned out, however, that it would be another six weeks before he would be shut down for the rest of the way.
Thursday's announcement closes the door on a disappointing first season for Irving in Brooklyn. He played extraordinarily well at times, including scoring 55 points in his first game for the Nets in a season-opening overtime loss to the Minnesota Timberwolves, but also spent the vast majority of the season watching in street clothes alongside Durant, who is out with a torn Achilles tendon and officially ruled out a return this season in an interview earlier this week with Bleacher Report.
Rather than figuring out how Irving fits next to Spencer Dinwiddie, Caris LeVert and Joe Harris ahead of Durant's return next season, the Nets saw them together for only 19 games this season. Now, Brooklyn will have to try to make the playoffs without Irving. The Nets entered Thursday seventh in the East, two games ahead of the eight-place Orlando Magic and five games ahead of the ninth-place Wizards.
Nets coach Kenny Atkinson admitted Irving being ruled out will force the Nets to start from square one in terms of piecing together their roster when their two stars return next season.
"I think that's the big thing," Atkinson said. "You wanted some time to work things out, work on our continuity and obviously work on the chemistry of the team and how we're going to use him. That's the disappointing part. We're not going to have that opportunity. We'll have to start fresh next season and figure it out quickly. But that is the disappointing part.
"I don't know if there's enough, especially when you throw Kevin into the mix. I think it's going to be a different structure, a different chemistry, different rotations."
That said, Atkinson was excited by the brief glimpses of what he saw from Irving, who averaged 27.4 points and 6.4 assists, on the court this season, and is looking forward to seeing more next season.
"I've said this before: He was better than I even thought, a better player than I thought, and I had tremendous respect for him in Cleveland and Boston," Atkinson said. "Faster than I thought, more skilled than I thought, a higher-level competitor than I thought, much more physical than I thought. I don't think people give him enough credit for how physical he is on both ends, how active he is defensively and what an attacker he is. That bodes really well for the future.
"I really love the player, and I feel like we have a really good relationship. So, we're in a good place there. Obviously, you want more reps, more time with him, but we'll have time with him in the offseason, too, to connect and, when he gets healthy, to work with him a little bit."
Marks said Irving is still evaluating his options and didn't say when he would have the surgery. But Marks did indicate that the rehabilitation process would allow Irving to be back before the start of next season.
"I think that is something that will have to be determined," Marks said of Irving's rehab timeline. "With all surgeries once somebody goes in there and takes a look at it then you evaluate how long the rehab is.
"This is something that he should be back in plenty of time to be working out this summer and obviously be ready for next season."
Like Atkinson, Marks was looking forward to having this season as an evaluation period for his newly built roster. The Nets signed LeVert and Taurean Prince to extensions before the start of this season, have to decide whether to do the same with Jarrett Allen before next season and have to deal with the free agency of Harris -- one of the NBA's best 3-point shooters -- this summer.
Marks will have to go into the summer and make those decisions without the benefit of seeing the full roster together on the court this season.
"I'd be lying if I said I wish all our guys weren't healthy for the whole time. It's been kind of a roller-coaster year," Marks said. "We've had Caris out as well. So we've had multiple guys who've had these strange, unforeseen injuries.
"But I have the utmost confidence in our performance staff, our doctors, all the specialists we've used as well. And also the guys. The guys have fought hard with their rehab and obviously that's led by Kevin over the course of the last four or five months while he's been a Net."