Headliner Announcement

Probably because Sonata Arctica doesn't have the pull for them, as some other bands. But Sonata Arctica has great pull for metal fans in general. That is why they are fit for the headlining slot.
 
When they were at the Galaxy in Santa Ana, the place looked packed. Seemed to be more people there for that show than when I saw Gamma Ray or Kamelot/Epica there. Maybe even more than Blind Guardian.

I don't think they will dissappoint.
 
I would say they have much more of a US following than Stratovarius or Angra who headlined PPVI. Probably Evergrey, too, who are usually an opener for their US shows. They drew extremely well in NY & Mass with local bands for openers so it was on their name alone. They also seem to be pretty popular among people who don't normally listen to metal.