I think what put Once on this Island over the edge in this close race (and it was close according to the NYTimes survey) was that there was a real passion and excitement behind it and its supporters were "ride or die" meaning they were not going to support any other show or waver from it. I think Carousel and My Fair Lady ended up splitting enough votes to hand MFL's defeat AND there wasn't the same passion or excitement behind MFL for various reasons I already stated (it being more expected, Lincoln Center being targeted as the giant Goliath v. the small David, Sher competing against himself, some industry backlash for hiring an outsider in Lauren Ambrose and they seem very protective of their Broadway actresses, etc.).
I said this in the other thread, but I was taken aback that for a show that was really second in Best Revival and received a lot of praise from the critics and in the nominations and people have been writing positive things about, there was certainly a lack of support at Radio City Music Hall. The performance seemed to garner a lot of support, but when they were handing out Tonys, MFL's nominees did not get the same screaming reaction the other nominees received. It was a lot more subdued. I wonder if there were some real anti-MFL bias going on. Earlier, GeorgeandDot asked why did people hate OoTI, but I think the real question is, why did people in the industry at the Tonys seem to have it out for MFL? I think it was for reasons really beyond MFL's control.