Okay, I'm going to say this one last time -- if Sheehan has really watched Buehrle pitch, would he be saying that Mark is nothing more than a middle-of-the-rotation pitcher?
You have seen Buehrle pitch and you seem to know that Buehrle is an ace or at least an extremely strong #2 so why doesn't Sheehan see this?
Just because his name is Joe Sheehan and he writes for "Baseball Prospectus" doesn't make his opinion any more valid than your's or mine. In fact, our opinions hold much more value than his because I guarantee you, Sheehan isn't watching 162 White Sox games every season.