It might also be cheaper to cool due to being set into the ground. I remember the City of Industry project being sunk into the ground in order to make it 'greener". It was easier to cool, which would likely be the case here as well. It seems very smartly designed, I'm interested in knowing more details, but it's hard to not be impressed thus far. There's still likely small tweaks to be made, but I don't think we'll see any major changes.
I would like to know what they'll do for a scoreboard though, while having the little wave thing is cool, it's similar to what they do at Staples. however I feel you still need some sort of scoreboard and HD video screen. I'm sure it's there somewhere though.