By now he's a familiar character in New York's downtown soccer crew— the floppy-haired guy, just a term paper taller than six feet, sweating on the turf below Delancey on steamy summer nights. He brings game—it's obvious; watch his quick feet— but what might not be so clear is that this playground soccer guy, the one pushing the ball upfield and later buying beers at the bar, is also a two-time NBA MVP.

This is how Steve Nash likes to spend his off-season vacation: quietly in New York City, in unpretentious parks like the...