The show should have been shot with a spherical lens. Only these effects shots would have been shot using an anamorphic lens.
What Eric Bruno is describing is slightly different, but the right idea. Cropping to 16x9 means removing vertical resolution, but you have to zoom the image to fill a 16x9 frame. With pan-and-scan, you're getting the same 4x3 image vertically, but losing horizontal resolution as you can only see a portion at a time.
This is what the anamorphic shots would have looked like:
It's a 4x3 shot much like any other, but has to be stretched in order to remove the distortion. More information in the same amount of space.
If you watch Sins of the Father, you might notice it looks noticeably different from the rest of the season. It looks much softer to me. I don't know if that's a result of the slight cropping/zooming or because it was done at the beginning of the process before they had fine-tuned their skill.