from the article:
As noted, Judge Ellis remarked upon Rod Rosenstein's conflict of interest in the investigation into whether Comey's firing amounted to obstruction of justice – a matter legally absurd enough on its face but made more so by the fact that Rosenstein himself (supposedly overseeing Mueller's work) was the very author of the memorandum to the president calling for Comey's firing.
But there's more.
At American Greatness, Julie Kelly indicates a ruling in which Mueller misrepresented to the court a significant matter that might well lead to his dismissal under the very law of his appointment.