WSJ called them out for fraudulently gaming proficiency testing:
> The two types of equipment gave different results when testing for vitamin D, two thyroid hormones and prostate cancer. The gap suggested to some employees that the Edison results were off, according to the internal emails and people familiar with the findings.
> Former employees say Mr. Balwani ordered lab personnel to stop using Edison machines on any of the proficiency-testing samples and report only the results from instruments bought from other companies.
> The former employees say they did what they were told but were concerned that the instructions violated federal rules, which state that a lab must handle “proficiency testing samples…in the same manner as it tests patient specimens” and by “using the laboratory’s routine methods.”
And they were very very careful and deceitful in their response:
> The sources relied on in the article today were never in a position to understand Theranos’ technology and know nothing about the processes currently employed by the company.
They were extremely careful in using the word "currently" - admitting obliquely that they'd changed their processes while making it seem that the employees didn't know what they were talking about. In reality, it appears that the former employees (and WSJ) rightly called them out for fraud, and somewhere along the way they "pivoted" to using standard techniques instead of the Edison snake-oil.