Hmmmm I don't hear Blaze being off key on Virtual... However, I put the weight on the voice because it contributes to the overall sound of the song, I mean, you can have an astounding performance musically speaking but if the singer sucks most common people are going to say the song sucks at least that's my experience. As an example, I know a lot of people that say that Death Metal songs are awful (although most of the musicians that I have heard are quite good) because of the gutural singers.
I don't think that the performance of the band in Virtual XI or even on The X factor are something special, but they, as always sound like Maiden...
Oh and by the way, I think that The Angel & The Gambler is by far one of the most if not THE MOST horrible & awful song of the Maiden catalog