Yes it's like that.
In important games as the playoffs or the semi-finals and finals of the national tournament there will be only 2 option to choose, as Damena said.
You can only pick "Playoff Normal" and "Playoff Crunch Time".
And indeed, if you start with enthusiasm 7 and you play "Playoff Crunch Time" your enthusiasm will stay at 7 untill it drops due to daily updates. If you play 'Playoff Normal" then your enthusiasm will increase just like you play TIE in the regular season.