The Brooklyn Nets went "all in" on James Harden, general manager Sean Marks says, making the decision to trade the former MVP "not easy".

After 80 games in just shy of 13 months, Harden has left the Nets for the Philadelphia 76ers in a blockbuster trade involving Ben Simmons.

The 76ers had been looking for a superstar in exchange for Simmons and were able to put together a package to tempt the Nets when it became clear Harden was open to moving on.

Harden had last January forced his way out of the Houston Rockets to move to Brooklyn and team up with Kevin Durant and Kyrie Irving.

But the Nets' 'Big Three' played just 365 minutes together across 16 games in the regular season and playoffs.

Although the Nets went 13-3 in those games, Harden and Irving were each absent for three games of the seven-game series against eventual champions the Milwaukee Bucks in the 2020-21 postseason.

The injury issues that dogged the trio last year have continued this season, while Irving has played just 13 games due to a refusal to be vaccinated.

The Nets, on a 10-game losing streak, are now moving in a new direction, but Marks insists their commitment to Harden up until Thursday's trade could not be questioned.

"Make no bones about it: we went all in on getting James Harden and inviting him to the group," Marks said on Friday.

"And these decisions to move on from a player like that, of that calibre, are never easy ones. I just want to be clear that this is not something that you think, 'great, let's just make a split decision and move on from that'.

"I give James a lot of credit for having open dialogue, open discussions with me and with the group, [Nets coach Steve Nash] and [owner] Joe Tsai and everybody over the last 24, 48 hours.

"Again, I said they're not easy, but I think that's something we pride ourselves on is being open and honest. James was honest with us and we were honest with him.

"I think it's a move that enables him to have a fresh start, enables this team to have a fresh start, without trying to push things to make things work.

"If we realise this is not going to work, short term or long term, then it's time to say for, both parties involved, this is better off."

Harden, whose 76ers debut is likely to be next week, will be warmly received in Philly.

Second-year point guard Tyrese Maxey welcomed the 10-time All-Star, who is set to shine alongside MVP candidate Joel Embiid.

"It's going to be great. It's two MVP-calibre players on top of what we have here already," Maxey said, adding: "It's going to be great, and I just can't wait."