Classically, jockstraps were worn with nothing else between them and whatever athletic pants you were wearing. Football and baseball players wore them under theirpants, sometimes with a cup jock ( which is different from just a plain jock) on top. Basketball players, too, wore jocks and shorts, as did soccer player.
I deplore the demise of the jockstrap. Compression shorts are no substitute, in my opinion, as they offer little support for low hanging nuts. Plus, what's more manly than a fuckin jockstrap? It used to be THE symbol for manhood. Too bad that's not the case anymore; just another example of the loss of ritual in America.