Mueller understands that frogs in a pot of slowly heating water will not notice the change until nothing can be done. He would much prefer that the frogs feel a sudden and drastic change so they will react appropriately.
Stated another way.
I knew Trump was a little dirty when I voted for him.
Okay, he's a little dirtier than I thought.
Okay, he's a little dirtier than I thought.
Okay, he's a little dirtier than I thought.
Okay, he's a little dirtier than I thought.
Okay, he's a little dirtier than I thought.
Yea, he's kind of filthy but I knew that all along.
or.......
I knew Trump was a little dirty when I voted for him.
Good God, I had no idea he was that filthy.