There's actually a valid discussion in there. I really consider this a JR/JP/JLB album. Yes JLB didn't write anything, but he put a voice to the work and clearly did more than simply sing the songs.
Myung and Mangini, however, I hate to say it but I barely notice they're on the album. I know there are bass and drums on the album, but theoretically it could've been anyone playing those parts. There isn't really any personality in the playing. I know JP and JR have been the primary writing forces since JR joined, but I think The Astonishing went even further with that.