I don't know how OVERrated they have been. I think they were overrated in 2001 based on the high expectations from the previous season. The past two years, baseball "experts" have had little good to say about the White Sox and basically nailed their problems on the head.
Even Gammons I remember said something like the Sox have problems giving up really big innings and having very key errors that give their opponents extra outs. To me, that was exactly what the Sox have done the past three years.