The prestigious sports website Grantland has admitted poor judgment and offered a profuse apology for an article about the inventor of a revolutionary golf club who killed herself while the piece was being researched, and whom it posthumously outed as transgender.

In a mea culpa that stretches to almost 3,000 words, Grantland’s editor-in-chief Bill Simmons writes that despite being extensively edited by multiple people, the ESPN-affiliated website had made the “massive mistake” of failing to have it read before publication by someone familiar with the transgender community.

He then lists seven errors of judgment contained in the piece that would probably have been caught and corrected.

“I want to apologize. I failed,” Simmons writes. “I realized over the weekend that I didn’t know nearly enough about the transgender community – and neither does my staff.”

The article at the centre of the firestorm was an 8,000-word investigation, eight months in the preparation, by a young writer called Caleb Hannan that was published last week. It focuses on a seemingly revolutionary putter called the Oracle GX1 that claimed to bring the aerodynamics behind golf clubs into the 21st century.

The heart of the piece was a deep dive into the mystery of the inventor behind the club, a woman called Dr Essay Anne Vanderbilt. As Hannan dug into her business and her creation he discovered extraordinary details about her that did not tally with the public story that she had presented to others, including investors.

In the course of his investigations, Hannan conclusively debunked several of the key elements of Vanderbilt’s resume – she was not one of the illustrious Vanderbilt family, she was not trained as an aeronautical physicist at MIT and she did not work secretly as a private contractor for the department of defense on projects including the stealth bomber. All of those details, most commentators have agreed, were legitimate territory in an article about an inventor who was making lavish claims publicly about her product and drawing investment on the back of it.

But Hannan also stumbled on another element of Vanderbilt’s story that she had worked assiduously to keep private: that she was transgender. As Christina Kahrl, a transgender ESPN sports writer invited by Grantland to contribute a guest column on Monday explained, the article’s several problems stem from this initial lapse of judgment – that it treated Vanderbilt’s desire for privacy about her gender identity as just one other aspect of her long record of deceit, rather than as an aspect of her private life that was irrelevant to the story and that should have been respected.

Among the most egregious errors that flowed from that central mistake, as Simmons itemises, was that Hannan outed Vanderbilt while she was still alive to one of her investors. “Caleb never should have outed Dr V to one of her investors,” the editor-in-chief says.

The article also contained difficulties of language. At times it broke from the style guide followed by outlets such as the Guardian and Associated Press of using the names and pronouns chosen by transgender people themselves – for instance, Chelsea Manning, the WikiLeaks source (formerly known as Bradley). The Grantland article said of Dr V: “What began as a story about a brilliant woman with a new invention had turned into the tale of a troubled man who had invented a new life for himself.”

At the moment that Hannan realises that Dr V is a transgender woman, he writes “a chill actually ran up my spine”. In his apology, Simmons says this displayed lack of sophistication on Grantland’s part – Hannan had meant to imply “this story is getting stranger” but to many it had come across as “Ew, gross, she used to be a man?”

A third problem raised by both Simmons and Kahrl was that in failing to understand the context of its subject matter, Grantland had failed to address a vital element of the story – that suicide rates among transgender people are dramatically higher than those of the general population. Kahrl notes that a recent survey found that 41% of transgender people in the US have attempted suicide.

In the course of his mea culpa, Simmons makes clear that Grantland does not plan to remove the article from its site. He explains why: “We’re never taking the Dr V piece down partly because we want peole to learn from our experience. We weren’t educated, we failed to ask the right questions, we made mistakes, and we’re going to learn from them.”