Former Microsoft CEO Steve Ballmer has lashed out at current CEO Satya Nadella's handling of the company, describing some of the company's accounting practices as "bulls---." Ballmer also criticized the universal app system in Windows 10, despite Windows 8 introducing a precursor to the system under his leadership. 

"Windows Store apps," which standardized the interface of apps for both touch and nontouch devices, was introduced with Windows 8 in 2012. But Ballmer seemed unconvinced on Wednesday that Nadella's expansion of the system to let the same app run on both mobile and desktop was the right step forward.

"That won’t work," Ballmer told Bloomberg, saying Windows 10 Mobile will need to be able "to run Android apps." Microsoft was working on a solution to this, known as Project Astoria. Last month, Microsoft said Astoria was "not ready yet" while sources said the project was not going well.

Ballmer also criticized the company's financial reporting of its cloud business. “They should report the revenue, not the run rate,” he said. The run rate takes current results and extrapolates them out to a yearly rate. 

Ballmer argued in cloud computing, margins are more important than in software. As the margins are thinner in cloud services compared to software, it becomes all the more important to see them to have an idea of how the business is doing.

IBM also used to avoid reporting its cloud revenue, instead reporting its cloud revenue growth rate. An investigation by the Securities and Exchange Commission into its financial practices concluded in June 2014 and found no wrongdoing. After this, IBM changed the way it reported cloud revenue.