Okay, I voted for Nastanovich. It was between him and Gary Young.
I think Gary Young contributed more to the sound of the band than any of the other guys on the list, but Nastanovich was like the glue that held them all together (until Gary fell off, then he held steve west on maybe?). Even sans-Young, he brought the weird. The weird that could be harnessed. A more disciplined weird than Young's, but a weird nonetheless. He was also a total mensch to Malkmus' brooding snob during a painful 120 Minutes interview with Lewis Largent (both guys were awesome in this interview as good-cop, bad-cop; Malkmus disgusted with Largent's quesions, Nastanovich engaging Largent to sing "November Spawned a Monster" with him), and he was the band accountant. So I voted for Nastanovich: Percussionist, Hype Man, Muse, Bookkeeper.
I guess that's all I ask, Matthew S.; that you follow your heart. What's more important to YOU: sonic contribution, or emotional contribution, or good-looks or what?