Wow, no wonder you thought Cadets should have won. It's the only show you pay attention to, heh. I'm not meaning to be rude, I'm just trying to point out that maybe you should try watching all the shows more carefully before stating a specific corps should have claimed the win.
However, you are right when you mention the "sinister concept". Their show is built on fantasy. If you actually watch the colorguard's main character, you'll notice him journeying from one side of the field to the other. Periodically, he chases after another main character, a girl he cannot quite get a hold of. Many obstacles get in his way, the brass, percussion, etc. They are supposed to be like fantasy creatures, that's why they keep climbing all over each other making funny shapes. The whole thing is kind of like a dream, until he wakes up at the very end to find himself exactly where he started.
The show is titled "The Grass is Always Greener," but it doesn't necissarily say "..on the other side."
I think it's very interesting, myself. I love this stuff.