I've never heard of anyone (particularly not someone knocked out of the cup) being at 16 enthusiasm a full day after their most recent match, but you can crunch it from here on out, sure.
You can always just playoff crunch it since it doesn't halve your enthusiasm, but my experience last season was that you can generally get through the div IV playoffs on playoff normal through the semis, quarters and first game of the finals and when you crunch it at the end you've got a big enthusiasm advantage to close things out. Of course your strategy depends on what you think the odds are of getting to the finals on normal effort.