You remember those velociraptors from Jurassic Park? How they learned? He's like that. The first game, you might just get him. But the second game, he will have already cataloged all of your tendencies, assessed your weaknesses and strengths, and constructed elaborate mind-mazes to trap you into a spiral of self-destruction.
He's also kind of like the aliens of the Aliens movie franchise. Just when you think you've got it figured out, and the face hugger is off and you are just sitting down to chow down with your buds because you made him punt once... and then BOOM:
He's ripping through your rib cage down the field for a touchdown, and you're dead.