No-one has endured more Stosur centre-court meltdowns than David Taylor, who linked up with the now world No.9 and grand slam champion upon her return to the game in 2008 after battling career-threatening illness.
Taylor was in Stosur's courtside box during her 2010 French Open final upset loss to Francesca Schiavone, just as he was when she thumped the unfancied Italian in straight sets in the opening round in Paris the year before.
Taylor's gut also churned when Stosur committed tennis suicide against another Italian she'd never previously lost to, Sara Errani, in the semi-finals at Roland Garros last year.
And he admits the 28-year-old's latest collapse - from 5-2 up in the deciding set against Zheng Jie at the Australian Open - was "one of her worst".
"It was terrible to see," Taylor told AAP.
"She served for the match twice on centre court and was absolutely dominant to that point.
"At 5-2, I put my phone in my pocket so I wouldn't forget it because I knew it was the last game.
"It is an absolutely devastating loss. It's illogical for a player of that level - but that's what it is. It's not that easy to solve. I know we're all trying pretty hard, but there's no easy answer."
Even if many may think so.
Past champions, current players, fans and critics have all offered advice - and Stosur has taken it all on board.
The Queenslander has embraced the spotlight, shunned it, gotten away and even publicly - and candidly - spoken of the mental demons that are denying her a truly great career instead of a one-slam one.
Nothing has worked.
But rather than bag her, Taylor wishes people, especially casual observers who don't truly know tennis, could try to understand.
"There's not one thing or suggestion that I've ever read that she hasn't tried," he said.
"People make statements as if it's something new. She's tried everything. Sports psychologists, you name it.
"She's one of the best players in the world so she's got access to a lot of information and these people are making comments like it's new.
"When I really got into coaching, I made sure I played competitions myself. I played club tennis in Switzerland because we all forget as coaches how hard it is.
"A lot of people who aren't in sport, I don't think they really understand.
"She's obviously very anxious and it's highlighted under pressure. It happens to people in everyday life. Her anxiety happens in sport."
And on some of the biggest stages in sport.
But just like Martina Hingis bounced back from her infamous French Open final meltdown against Steffi Graf in 1999 to reach another three consecutive Australian Open finals from 2000 to 2002, Taylor is backing Stosur to rebound.
Taylor speaks from experience because he happened to be in Hingis's courtside box in Paris that afternoon too.
"I was with Hingis as her sparring partner. It was a lonely box in the final," he said.
But there have been happier times too, namely Stosur's memorable 2011 US Open final triumph over Serena Williams just months after the Australian's title defence in Charleston ended in tears after a loss to lowly-ranked Elena Vesnina.
And Taylor, who doesn't subscribe to the theory that Stosur's mental struggles are any more pronounced in Australia, has no doubt there will be more happy times ahead.
"The thing is, she was two points from the match against Zheng and then everyone would be writing a different story," he said.
"So I think she can rebound quickly, but it is very difficult. Unfortunately, a lot of questions are raised and you need to come up with the answers.
"But the thing that she's proven to everyone and herself is that she rebounds quickly and plays good tennis after disappointing losses.
"She has had shocking results at Wimbledon every year, played a terrible match at the French Open - it wasn't in Australia.
"It's just highlighted because she is in Australia."