I think home court advantage boosts your team's ratings like 2 or 3 points of enthusiasm.
So, for example, playing home with an enthusiasm of 5 is equivalent to playing away with an enthusiasm that is somewhere between 7 and 8 (let's say 7.5).
So, playing a game home instead of away makes a lot of difference: you get +2.5 enthusiasm because you play home, and your opponent doesn't. In other words, clinching a better regular season record than an opponent you will meet in the playoffs gives you a net +5 enthusiasm bonus compared to having a worse record. That's an effect often underestimated when TIEing all games at the end of the season.