I'm sorry, but screw the Rich Hill experiment. Williams is only 24, has had major league success, and is starting to throw the ball well @ Iowa. I'd much rather see Williams up, than watch Hill get shelled for a 16th, 17th, 18th, and 19th time.
It just seems Hill doesn't have the stuff or mental makeup to make it in Chicago. If Williams has a few good starts, they might have a 5th starter for next year, and some teams might start a calling, as well. This is the same guy who had a 3.30 ERA @ age 21, and a 4.25 ERA @ age 22, and a 3.91 ERA last year w/ the Cubs.