Half a singer midget's weight in a bathing suit

Since his death in January, I've been reading more John Updike lately. I read The Witches of Eastwick (more sinister and entertaining than the Jack Nicholson vehicle) and I'm currently reading The Centaur. I also read his famous article on Ted Williams, Hub Fans Bid Kid Adieu, to get in the mood for the upcoming baseball season. In the footnoted version of the article that I read (the footnotes aren't included in the linked version), I came across a famous quote from one of Ted Williams' early critics, Bill Cunningham. He said, "I don't believe this kid will ever hit half a singer midget's weight in a bathing suit." A horribly inaccurrate prediction, yes, but also an odd and perplexing (not to mention crude and insensitive) metaphor. The first time I read it I didn't even understand it. The word "singer" threw me off. I mean I grasped that he was trying to imply that Williams' batting average would be a low number, but why was it necessary to also include the midget's occupation? Were singer midgets dramatically lighter in weight than other midgets? I still don't get it.