Lets be honest, most nations have horrible boring national anthems that were chosen to honor some poet who wrote an inspirational thing during some war. Usually it wasn't even a song. Singsong warbling that nobody would be listening to if they weren't stuck with it as their national song. In fact, people from some of the most nationalistic countries in the sport are likely to sing monosyllables not even in the song, over the top of the song, for the whole song. And most of them don't even say anything about their country or their national history. Australia has some natural resources, yay. Have a wombat sing the song and I might even stay awake. God Save the Queen, that's nice, the Queen is a fine lady. But the song is a snoozer. The US anthem can be a fun song, but how many people even know the words? The audience? "Blah blah blah... and the home of the braaaaaaaave." Its too hard for most singers to even sing it. Probably because it was written as a poem.
The only country whose national anthem I want to sit around listening to is Scotland, and they have the good sense to always do the instrumental version. And Scotland has, I think, one MMA fighter, right? One? And Calderwood isn't always one of the fighters. Usually it would be some nonsense where you can't hear the music, all you can hear is "who-ah, ew-ah, who-ah, ew-ah, who-as, er-ah" from the crowd for 5 minutes. And that's the national song for like 10 countries, from Ireland to a bunch of places in South America.
It works better in baseball, where you're expecting to stand around and enjoy the scenery most of the time, and people want to stretch their legs before the game.