In an interview with Bloomberg on Wednesday, the former Microsoft CEO took aim the company’s handling of financial disclosures, among other issues. Ballmer, Microsoft’s largest individual shareholder, critiqued the company’s decision to share a run rate for its cloud business rather than actual revenue.

“It’s bulls–t,” Ballmer told Bloomberg on the sidelines of Microsoft’s annual shareholder meeting on Wednesday. He added that he has brought up his concerns with Microsoft, to no avail.

Microsoft’s decision to share run rates in its financial disclosures instead of actual revenue is a controversial one. Revenue provides a clear picture during a specified period about how a particular business unit is operating. Run rate, however, takes a snapshot of performance at a specific point in time and then extrapolates that over a set period. In Microsoft’s case, it projected a full year of revenue.

In October, the company reported that its cloud revenue would top $8.2 billion on an annualized basis. It added that it was on track to reach a goal of $20 billion by 2018. Microsoft does not report actual sales for its entire cloud operation.

But Ballmer didn’t stop there. According to Bloomberg, Microsoft CEO Satya Nadella was asked to explain how the company would get more apps to Windows-based mobile devices. Nadella said that a core part of his company’s strategy is to make it easier for developers to create universal apps that could run across all Windows versions, including those on PCs, smartphones, and tablets.

Ballmer, according to Bloomberg, couldn’t stay quiet during Nadella’s response. As his successor was speaking, Ballmer was heard saying that Nadella’s plan “won’t work,” adding that the secret to getting Windows smartphones running more programs is to let them “run Android apps.”

Ballmer’s comments have, of course, caused a stir in Redmond and among shareholders. Since his ouster in 2014, Ballmer has remained largely tight-lipped about Microsoft and his successor. He has focused much of his time on operating his NBA team, the Los Angeles Clippers, and in October, bought a 4% stake in Twitter (TWTR).

Despite the relative silence, Ballmer has long been viewed as one of the company’s most ardent supporters, making his latest comments even more surprising.

Ballmer joined Microsoft (MSFT) in 1980 as its 30th employee. After Microsoft co-founder Bill Gates stepped down as CEO in 2000, Ballmer took over to handle the company’s finances and daily operations. While Gates still played a major role at Microsoft as chairman, he gave up his day-to-day role at the company in 2006, leaving Ballmer in full control. During his tenure as CEO, Ballmer tripled Microsoft’s annual revenue to nearly $78 billion. The company’s profits ballooned to $22 billion during his last full fiscal year as CEO.

Despite seemingly strong financial performance, Ballmer’s reign was soured by Microsoft’s sluggishness to focus on mobile, allowing Google (GOOG) and Apple (AAPL) to establish dominance that the company hasn’t even come close to overcoming. Ballmer was similarly slow to move to the cloud—another burgeoning industry segment—and was roundly criticized by analysts and shareholders for seemingly killing projects that could have hurt the company’s main attractions: Windows and Office.

By 2013, after years of shareholders complaining, Microsoft finally announced that Ballmer would retire, and in early 2014, Nadella took the reigns. Despite Microsoft calling Ballmer’s departure a retirement, analysts widely believe that the board nudged him out to let new ideas filter in.

With Nadella, those new ideas have indeed filtered in. The current Microsoft CEO has written a new mission statement, redirected the company’s focus to “mobile-first, cloud-first,” and took steps that would have never happened during Ballmer’s days, including offering its latest operating system, Windows 10, for free.

Still, Ballmer looms large in Redmond. As owner of over 333 million shares, Ballmer controls more of Microsoft than Gates, who owns 223 million shares. That alone gives him significant clout at Microsoft.

Ballmer has not commented publicly since his statements at the annual meeting. But the very fact that Ballmer—one of the most dedicated Microsoft supporters ever—so publicly spoke out against his former employer, is at the very least remarkable.

For its part, Microsoft isn’t showing any sign of discord with Ballmer. In a statement to Fortune, Microsoft’s general manager for investor relations, Chris Suh, seemed to convey that Ballmer’s comments do not trouble the company, and the software giant is fine with its former chief executive speaking his mind.

“We enjoy a regular dialogue with Steve, and welcome his input and feedback, as we do from our other investors,” Suh said.

For more on Steve Ballmer and his ‘craziest’ moments, check out the following Fortune video:

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