On the day David Wright underwent surgery to repair the herniated disc in his neck, manager Terry Collins, voice heavy with resignation and tinged with sadness, acknowledged the difficult truth that everyone has known for a long time. If Wright comes back — and right now, that’s still a big if — he will never be the player he used to be.

Which makes Wright’s stalwart determination to return to the baseball diamond all the more remarkable.

“It’s been very hard,” Collins said Thursday, repeating the phrase for emphasis. “I was sad . . . In your mind, you know how good he is, or at least how good he was, and to see those guys struggle and get frustrated because they can’t do the same things that they’re used to doing, it’s tough to watch.”

“[But] his whole thing was, ‘I’m going to get fixed. Whatever it takes, let’s just do it.’ ”

The Mets said the surgery — a cervical discectomy and fusion to remove the herniated disc and stabilize the area — was successful. The procedure was performed by Dr. Robert Watkins in California Thursday. Wright will undergo a rest period before resuming physical activity, the team said.

There is no timetable set for his return, though Collins classified two months as a best-case scenario, and the Mets said they would assess the situation after they see how Wright progresses in his recovery. Wright — already battling the degenerative spinal stenosis that cost him over four months last season — has said that his stenosis makes it difficult to get out of bed some mornings, and, prior to the new injury, he would have to warm up for hours just to be ready to play.

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Even in a prepared statement, Wright’s frustration shone through.

“After trying every way to get back on the field, I’ve come to realize that it’s best for me, my teammates and the organization to proceed with surgery at this time,” it said. “My neck simply did not respond to any of the treatments of the past few weeks. While incredibly frustrating and disappointing, I am determined to make a full recovery and get back on the field as soon as I can to help the Mets win. I greatly appreciate the support of my teammates and our fans throughout the last few weeks.”

Wright, who was forced to take games off because of his back, hasn’t played since May 27. He was hitting .226 with seven home runs, along with 55 strikeouts in 137 at-bats. But despite his drastically waning production, his leadership was never questioned, and his desire to keep playing manifested itself in dramatic ways.

“He was at the park at 11:30 for an 8 o’clock game, to stretch, to massage, and to do all the things that just enabled him to get back on the field,” Collins said. “It shows you his dedication to be as good as he can possibly be and how he feels about the game and how he feels about this organization, that he’s got to be the guy and he did whatever he could to be that guy . . . This guy is one of the best I’ve ever been around.”

Neil Walker — someone who Collins has touted as one of the clubhouse leaders who have stepped up in Wright’s absence — said the Mets would have to make psychological adjustments as well as practical ones.

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“His presence especially is something we’ll miss as a group,” he said. “Obviously, if we can get him back in here just to be around us, it would be an uplifting thing. Certainly, you feel for him and you see what he goes through to prepare himself, how hard he works, so to see him have to go through surgery is no fun. Our thoughts are out with him today.”

The Mets on Thursday prepared a get-well video for Wright. Wilmer Flores started at third base, as he will for the foreseeable future, Collins said, adding that the Mets are examining all options — including the most difficult one of all, the possibility of baseball life without Wright for good. The manager only lightly touched on this, yet another uncomfortable truth.

“I have no clue what the mending period is,” Collins said. “I have no clue what to expect. We have not heard one word of ‘Hey look, he’s going to be back, 100 percent.’ I have not heard one word.”