After crashing out of the NBA playoffs with the Philadelphia 76ers, Ben Simmons withdrew from Australia’s Olympic basketball squad on Tuesday, with the national team officials saying he was having a “rough time” in the NBA and wanted to focus on improving his skills.

Earlier this month, when the top-seeded 76ers were bundled out by the unfancied Atlanta Hawks in the Eastern Conference semis, Simmons seemed like he couldn’t even shoot for his. 

The 24-year-old guard was heavily criticised for his performance.

National coach Brian Goorjian said he and the rest of the squad backed Simmons’ decision and hoped he would represent Australia men’s basketball team, nicknamed Boomers, in the future.

“It is a pretty rough time for him right now and I know it (the Tokyo Olympics) is something that he wanted to do, but the timing just hasn’t worked,” Goorjian said in a statement, according to AFP inputs.

“The best thing for everybody right now is for him to go on and develop that skill package and improve in a couple of areas for his next season in the NBA, but the Boomers are always here for him.”

Ranked third in the world, Australia are hoping to make a mark at the delayed Tokyo 2020 Olympics next month and Simmons was expected to be the talisman in their quest for a first Games medal.

However, Simmons is yet to play for the national team, which made former Boomer and NBA star Andrew Bogut question his commitment.

“To be too blunt, if you need to be recruited to play for your national team and have a presentation about why you should play, you shouldn’t play,” Bogut told Fox Sports Australia after the latest withdrawal.

“It’s bittersweet. We don’t really know what he can bring because he’s never brought it for the national team.”

Meanwhile, veteran Patty Mills, who is expected to lead Australia in Japan, said Simmons would face no criticism from within the squad.

“We support each other through the good, bad and ugly, whatever it may be, and Ben isn’t an exception to that,” he said.

“No matter what he does, myself and the team will continue to support him because this is a safe place.”

Simmons’ future with the Sixers is under a cloud, with US media reporting the Eastern Conference franchise want to offload him.

The Boomers will go to Tokyo also without former Dallas Mavericks swingman Ryan Broekhoff, who quit last week citing mental health issues, and centre Isaac Humphries, who has a foot injury.

The 16-man Australia squad are currently assembling for training in Las Vegas, where they will be cut to 12 early next month before playing exhibition matches against the United States, Nigeria and Argentina.