What three-parter are you talking about? And how were any Vulcans other than T'pol off base? They explained that T'pol was more emotoinal due to the stress of how the humans treat her, and due to her drug problem. But I don't know what you're referring to with the Vulcans as a whole being off base.
Didn't they have some whole arc about a Vulcan guy trying to get the other Vulcans to see that they'd lost touch with the teachings of Surok, and the Enterprise crew having to find a young T'Pau?