INDIANAPOLIS — When Bob Bowman was coaching the world's greatest swimmer, he'd be the first to concede he was not a very nice person at the pool.

Screaming, berating and belittling were an accepted part of the package.

Given that Michael Phelps won 23 Olympic gold medals, Bowman had little reason to question his over-the-top techniques.

Then, Phelps retired.

And Bowman took a good, long look at himself in the mirror.

He didn't like what he saw.

"The toll it took on me. It was exhausting," said Bowman, a bit of regret in his voice. "And it's just not good practice."

Make no mistake, Bowman is as hard-nosed and demanding as he ever was.

He just conveys that message in softer tones these days.

"I'm so different," the 58-year-old Bowman said, breaking into a nervous chuckle when asked specifically what that means. "Like, a human."

His swimmers back up the kinder, gentler assessment.

"I'm really proud to see where Bob is at now," said Chase Kalisz, who was coached by Bowman growing up and returned to his training group this season. "There's a lot less stress and there's a lot less pressure. He really is enjoying everything he's doing. You can see he enjoys and really cares about everybody in our group. We have a ton of fun."

Then Kalisz passes along some intel that would have seemed unfathomable in Bowman's younger days.

"Bob didn't yell at me once this year," Kalisz said with a big grin.

After being based in Baltimore for most of Phelps' career, Bowman was looking for new frontiers when he took the head coaching job at Arizona State in 2015.

Phelps had come out of retirement for one last Olympics, but Bowman knew the Rio de Janeiro Games would be his star pupil's farewell.

"Michael was gonna be done and I needed a challenge," Bowman recalled. "I was too young to quit. I didn't know what else to do."

He wasn't an immediate success at Arizona State, but the program — both the college team and the pro training group — began to improve as he put his stamp on it.

Albeit, a much calmer stamp.

Noticing that success, more and more swimmers began to flock to the desert to work with the coach who coached Phelps.

Twelve of Bowman's swimmers are competing for the US and other countries at the ongoing world championships in Fukuoka, Japan — most notably, rising French star Leon Marchand, who has drawn comparisons to Phelps.

Bowman has proven he can be highly successful even without the greatest swimmer of them all.

"It's very satisfying," Bowman said. "It took us a while to get here. But having gone through that process, it definitely makes it satisfying to know that we can kind of do the things we're doing now."

Bowman has been like a father to Phelps, who is married with three young sons — youngsters the coach views as his grandchildren.

Being around Boomer, Beckett, and Maverick helped smooth out the cruel edges of Bowman's coaching demeanor.

"When I think about my grandchildren, I don't want them being angry at people all the time," he said. "Then I go back to practice and I'm like, 'Wow, these kids have a grandpa too. I wonder how he treats them?' Probably a lot nicer than I used to treat my swimmers."

Looking back, Kalisz has no regrets about working with Bowman in his more intense days.

"There were a lot of times I needed a kick in the (butt) and Bob gave it to me," Kalisz said. "I'm thankful for it because it prepared me for pretty much every single situation you can run into, all the adversity that you can come into.

"We trained under stress and pressure," he added. "You were worried about getting yelled at every single day. That's what comes along when you're training next to the greatest Olympian of all time."

While Bowman may have turned down his voice level, he's not gone all soft.

"I don't want to say it's laid back, because the intensity is maybe as high as it ever has been," Kalisz said of the atmosphere at practice. "But I think we found a flow and a rhythm to everything."

Former world-record holder Regan Smith has revitalized her career since joining Bowman's program last fall. While stressing that she hasn't worked so hard in her life, she seems a bit incredulous that Bowman used to be such an ogre on deck.

"He's so patient with me," Smith said. "I've never been yelled at or anything like that. He's not going to be mean to you if you do your work, and you work hard, and you make him proud. That's all I want to do."

Smith has certainly taken to Bowman's straightforward approach, which helped her overcome some of the mental challenges she faced after setting world records in the 100-meter and 200m backstroke as a teenager in 2019. For the next three years, she struggled to live up to those expectations.

"What I respect about Bob is that he doesn't over-complicate things," Smith said. "Whenever anyone gets too inside their head and complicates things, you're not gonna see good results. He keeps it so simple, which I love. He knows what he's doing. He knows what works."

Bowman doesn't even have to scream to get that message across.

"I don't do that anymore because it doesn't work," he said. "I wish I had known better earlier."

Agencies via Xinhua