Tennis legend Boris Becker on what he's learned after 'fall from grace' and prison sentence

Boris Becker has been called many things over his four decades in the public eye: tennis prodigy, Wimbledon champion, heartthrob, playboy, bad boy, Boom Boom. Husband, dad, divorcé, liar, convict.

Becker's heard it all. He's got another name to add to the list: "A mensch, I'm a real mensch, with qualities and weaknesses," he told ABC News in a recent interview from Dubai.

The occasion was the release of the Apple TV+ documentary "Boom! Boom! The World vs. Boris Becker," which traces his decades of international tennis success -- including the three Wimbledon championships, starting at 17, which still make him the youngest men's singles winner ever -- followed by personal downfall, resulting in Becker being convicted and sentenced to prison in the U.K. last year after prosecutors said he hid some of his wealth related to his bankruptcy in 2017.

Did Becker blanch at the documentary when first approached about participating and, with director Alex Gibney, reliving ... everything he'd been through?

In his telling, not at all.

"I'm all in, either I'm with you or I'm not with you, I'm not halfway," he said.

The series of interviews he gave Gibney, including just before he went into prison, were an opportunity, he said: "I felt like setting the record straight with an expert."

He calls the result a "labor of love" -- and an emotional one at times, such as looking back at the extensive archival footage from which Gibney drew. "I've been crying a lot when I watched it because of some of the good moments. I've been crying a lot [because of] some of the bad moments," he said.

"The World vs. Boris Becker" starts from the beginning and, using Becker as a guide, trails after him through the twists and turns of his life: what his legendary tennis skill earned him on the court and the choices that consumed him off of it, with the tabloid fodder of his personal life constantly churning in the headlines.

Beyond Becker, the documentary includes interviews with other tennis legends and some of Becker's inner circle through the years -- a mark, director Gibney told ABC News, of Becker's generosity with his own time and in urging others to speak out.

One of the things that drew Gibney to Becker was Becker's sense of himself -- how he "was a storyteller in the greatest sense of the word," both in talking about tennis and talking about everything else.

"I always wanted to reach for the stars," Becker told ABC News. "I did reach a few, but also I reached the bottom as well."

And one of the themes Gibney wanted to explore was that power to self-mythologize: where it touched the truth and diverged from it.

"That, I think will be the test for Boris going forward: He's always shown that brio, that sense of self confidence, question is going forward for him -- can he continue to explore that sense of vulnerability that allows you to be truly honest with yourself?" Gibney said.

"A rather peculiar talent of Boris' was that he had, he was so gifted athletically, but I think he would let his mind wander to some extent until he was in danger of losing," Gibney said. "And that seemed to allow him to focus in a way that he wouldn't otherwise do."

As someone who knows Becker well suggested to Gibney -- it's like a hand being drawn to a flame. How close can you get without burning up?

"[It] worked for him at times and also not so much at other times, particularly not in real life," Gibney said.

Freed from prison in December, after serving eight months, Becker quickly returned to his native Germany. The new documentary and his related press tour are his most extensive comments on what his defense attorney has said was worse than a "fall from grace."

"While I accept your humiliation as part of the proceedings, there has been no humility," Judge Deborah Taylor told Becker last April.

That's not how he sees it now.

"I had a lot of time to reflect," he said of his 231 days behind bars, which he describes as harrowing, disorienting and "very, very lonely." Whatever preparation he did before prison couldn't really prepare him, including for the crowding sense of danger.

As he adapted, he looked inward.

"I've noticed a couple of wrong choices," he said with a light laugh. "I've realized a couple of mistakes. I know why I was incarcerated, I think that's the most important ... I've accepted that."

He's learned this, too, he said: "If you're not really looking for answers, you haven't been there long enough." (And one other lesson -- "to shut my mouth a bit more," he added.)

Becker said he's proud of the documentary and stressed that he wanted no kind of editorial oversight. Speaking with ABC News, he quibbled with how he is depicted and, despite acknowledging what he's done wrong, could not resist pushing back on "a couple of financial facts" and some "far-fetched" statements from prosecutors.

But he described being less interested in the past than the future. "The choices I make now are a reflection of the lessons that I've learned," he said.

He's not been shut out from the world of tennis, for which he said he's grateful. So much of "The World vs. Boris Becker" is about the life of a champion athlete -- its thrills and perils; the sheer willpower it requires; the injuries and sleepless nights it exacts and the ever-approaching cliff at the end of one's sports career where the money immediately begins to evaporate, even if the spotlight doesn't.

Showing those struggles was important to Becker as well.

"Be careful," he said. "You're not always going to be on top."

What's next? Becker's partner, Lilian de Carvalho Monteiro, is there "through thick and thin" and he said his career leads right back to tennis, where he's been working in broadcasting. For all that the documentary might enlighten his many fans, he still has plenty of critics.

Challenges lie ahead, of course. Becker won't deceive himself on that.

"It's up to me to make the right choices and to make the right decisions," he said, "and to make them trust me again like I've done before."