The underlying infrastructure (connectivity) has to be there for OpenDNS to work. If the underlying infrastructure is misbehaving, OpenDNS isn't gonna make things any better.
My understanding was the problem was Comcast’s DNS servers were having the problem - not the connectivity itself. I’m in Indiana on Comcast and, I believe, ultimately go through the Chicago backbone as well but haven’t had any issues (and I use OpenDNS)