I'd go "normal" enthusiasm in the last game, then Playoff Normal in your first round. No reason to wreck your enthusiasm if you think his is low.
IMO, this is what I would do, if his Enth is low he will not want to burn much more so he doesn't get smashed in the first final himself, also if you have high Enth it will probably act more like CT in a Norm setting anyways.
Make sure you still scout your tactics and make sure you give your guys a good chance this way first.