Wide range of body types for Olympic athletes...I recommend The Sports Gene for an overview of the physical qualities needed for excellent performance.

They have a wide range of body types... for elite world-class one-out-of-millions competition, where even the tiniest differences like favorable genetic mutations make a difference. This in no way disproves the idea of an SQ, any more than grades in a math graduate course outpredicting an IQ test for who will win a Fields Medal would disprove the idea of an IQ test.

A sports quotient isn't a totally crazy idea, but I think it makes more sense as "can play a number of sports reasonably well" measurement rather than measuring the likelihood of achieving excellence at any sport.

Generally speaking, it's usually possible to devise a test for a specific field which outperforms an IQ test, adds predictive value above and beyond IQ. What's interesting about IQ is how general it is, how early in life it starts being useful, and how most good field-specific tests will subsume or partially measure IQ as well.