It was a minor, nothing-with-nothing trade at the time. But it now goes down as another Phil Jackson blunder.

Usually a bonus to finishing with the NBA’s worst record – which the Knicks did for the first time since 1985 – is having the first pick of the second round. Teams treasure that slot more than late first-round picks because of its economics.

However, that 31st pick was traded a long time ago — at the end of Jackson’s first training camp as Knicks president.

In a deal made nearly five years ago that now stings, Jackson traded away Travis Outlaw’s contract to the Sixers for the contract of Arnett Moultrie’s. The deal saved Knicks owner James Dolan about $4 million off the team’s 2015 luxury-tax bill. Both players were waived immediately.

In making the savings, Jackson had to entice Philly by adding the Knicks’ 2019 second-round pick. It only gets better.

Jackson made the deal also so he could open up a roster spot for undrafted rookie UCLA forward, Travis Wear, who was out of the NBA after playing 68 games.

It all turned out fortuitous for the Nets. The Sixers subsequently traded the Knicks’ 2019 draft pick to the Nets last season for Trevor Booker, but mostly so they could get rid of massive draft bust Jahlil Okafor.

The Knicks, meanwhile, have a second-round pick in this draft but it’s not a favorable one. They have Houston’s selection and that will be No. 55 in June 20’s draft.

It is one factor that makes the Knicks open to a draft day deal in which Frank Ntilikina could be on the move if the Knicks can obtain a late first-rounder or a pick in the 30’s. If Ntilikina is traded for a draft pick, that would open an additional $5 million in cap space next season.

Selections in the 30s are considered more golden than late first-rounders because the salaries are usually minimum deals, and not at a set guaranteed first-round rate under the CBA. The Knicks are also on a roll at that slot, having taken rookie center sensation Mitchell Robinson at No. 36 (a pick obtained in the Carmelo Anthony trade).

How Jackson obtained Outlaw’s pact in the first place is also sketchy. Jackson acquired him in his first offseason as a throw-in to snaring Quincy Acy. The Knicks dealt Wayne Ellington’s pact and former big-man prospect Jeremy Tyler for Acy and Outlaw.

Since the season ended, Knicks management has trumped up the notion they have seven first-rounders over the next five years.

However, two of those first-rounders – the ones they got from Dallas in the Kristaps Porzingis deal – are still uncertain.

If the Mavericks move into the top 5 in May 14’s lottery, the Knicks won’t get Dallas’ pair of first-rounders until 2022 and 2024. (The later one is top-10 protected). If Dallas remains locked at the ninth seed, that picks goes to Atlanta and the Knicks will get the Dallas’ picks in 2021 and 2023. Management considers both picks as possible trade pawns.

The Knicks’ 17-65 record gives them a 14-percent chance of winning the lottery and they can’t fall past No. 5. However, their league-worst mark could have been sweeter if not for Jackson.

Knicks GM Scott Perry told The Post on Wednesday the club would accept phone calls even if they land in the top 3.

“We’re going to be prepared no matter what happens,’’ Perry said. “We have a lot confidence in our staff and our process and how we go about evaluating players. We’ll be able to find a player that can help us get better. To what degree, we’ll see.”