Why does Manafort's judge keep berating the prosecutor?

For the last week, political junkies have been transfixed by the federal criminal trial of Paul Manafort, President Donald Trump’s former campaign chairman. It’s the first of special counsel Robert Mueller’s prosecutions to go to trial and, despite its rather dry focus on tax evasion and bank fraud, it’s been a reliable source of click-worthy developments: $15,000 ostrich jackets! Ukrainian oligarchs! Rick Gates confessing to crimes and an affair on the stand! Every day brings new drama.

Judge T.S. Ellis, the senior federal judge presiding over the trial, has made it even more cinematic. Ellis is plain-spoken and forceful and doesn’t hesitate to criticize the prosecutors. The news has been filled with stories of his rebukes, including interrupting the prosecutors’ opening statements to remind them that Manafort’s being wealthy isn’t a crime, berating them for introducing exhibits too slowly, demanding that they move faster, narrowing the evidence they’re allowed to present and accusing a prosecutor of “tearing up” during a tense exchange. He even takes shots at the prosecution’s witnesses, as when he told Rick Gates that Manafort couldn’t have kept too close an eye on his money if Gates was able to steal some of it.