CLEVELAND — Brian Cashman insists he did not need the strong — healthy — late run by Greg Bird to know that he was the first baseman not just now, but moving forward.

From the past, Cashman had not just Bird’s 2015 strong cameo while filling in for an injured Mark Teixeira and a powerhouse spring training this year, but also reports consistently stating that Bird was the best hitter in a farm system that also contained Aaron Judge and Gary Sanchez.

As for the future, Cashman did not obfuscate at all. He said, “we are getting under the threshold next year.” That means the $197 million luxury tax line for 2018. Translation: A big-ticket item such as free agent Eric Hosmer will not be signed when the Yankees can pay a player they have such high regards for around $600,000 next season.

“Bird is our first baseman moving forward,” Cashman told The Post. “We haven’t had [offseason] meetings like this, but the exclamation point is we are getting under the threshold next year. Bird is our first baseman moving forward because obviously we believe in him and also because of the cost control. The most important factor is if Bird is worthy enough to be our first baseman and our answer is yes.”

The Yankees have about $113 million committed to seven players plus the $5.5 million they will pay toward Brian McCann’s salary next season. That includes Masahiro Tanaka’s contract, though he could opt out but the strong likelihood is that he does not.

The Yankees will have about another $35 million-ish for arbitration eligibles that will include Didi Gregorius, Sonny Gray and Aaron Hicks. Each team will be charged roughly $14 million in 2018 for items such as insurance and pension. The 25-man roster has to be finalized around non-arbitration-eligible players such as Aaron Judge, Gary Sanchez and Luis Severino and, yes, Bird. Between that and what must be budgeted for call-ups during the season, you can add at least $10 million more.

Once you also put away some dough to make in-season trades, well, you see there will not be a heck of a lot of cushion left to sign a big-ticket item such as Hosmer, even if the Yanks decide to trade a player such as Starlin Castro or David Robertson. The advantages of avoiding more ominous penalties than ever before for being a repeat offender for being over the luxury tax and re-setting the tax to a lower level in anticipation of the starry free agent class after next season is just too strong for the Yanks not to get under the threshold in 2018.

That is why the Yankees feel blessed that they have assembled what looks to be — for now — a low-cost, high-impact positional core around Bird, Gregorius, Judge, Sanchez and they hope soon Gleyber Torres.

Cashman says he never had doubt that Bird would fit into that cornerstone. The Yankees GM said he did not see Bird’s several injuries as suggesting he will be susceptible throughout his career and believes the first baseman has a strong passion for the game.

So at the trade deadline Cashman did not look to solve first base long term and left even wiggle room this year if Bird could return from right ankle surgery.

That proved wise. Bird made it back Aug. 26 and hit eight homers with an .891 OPS in his final 29 games. That included a season-ending tear over his final 14 games — in which the Yanks were 10-4 — that Bird hit six homers and had a 1.168 OPS.

“I did not need the end of the year to know it [about Bird], I knew it,” Cashman said. “I liken it a bit to Bobby Abreu. The whole industry knew Bobby could roll out of bed and hit. He did not need much preparation. He was such a gifted athlete and hitting naturally came to him. I feel Bird is the same way.

“The downtime was so long, yet as long as [Bird] was healthy I thought it would not take him much to get him going again…. That is why I did not have much worry about the lost time, because [Bird] is so unique.”

Bird, who turns 25 next month, has actually moved well post-surgery, particularly on defense. He has had at-bats not just of production, but patience too. In the wild-card game Tuesday, his RBI single off Jose Berrios in the third inning gave the Yankees the lead for good in what would be an 8-4 triumph.

It was yet another late-season moment when the Yankees could feel good about their first baseman, not just for now, but the future.