On Saturday, Lawfare blog editor Benjamin Wittes wrote that the worst-case scenario for the Trump White House was if Mr Comey appeared before the congressional committee and was tight-lipped.
A loquacious Comey, he said, was evidence of an investigation that was near its end with little evidence of substantive wrongdoing in the higher levels of the Trump brain trust.
But what would happen, Wittes wondered, if Mr Comey's FBI investigation is turning up real evidence?
"In this situation, I would expect him to be minimally verbal. He may have to answer yes or no questions in certain instances, including about the truth of the wiretapping allegations, but he will refuse to answer a lot of questions. He will make as little news as humanly possible. He will be exceptionally spare with his opinions."
"I'm trying to be studiously vague to protect the integrity of the investigation," Mr Comey said at one point on Monday.
Wittes has since parsed the director's words and concluded that it was a bad day for Mr Trump.
"Really bad."
Mr Comey's relative silence could be deadly
.