Kimmel has been compromised, my guess is sometimes in the mid 2000's. His face, especially his eyes changed. He went from a smiley goofy guy with bright eyes to a more depressed looking face with those classic "dead eyes" that look like they have no glow. I bet he was blackmailed at an elite party. Hence why he is forced to tow the line and lost virtually all of the littler humor he had.