Here are some photos of Navy men from the 1940s in their jockstraps. You can see how the jockstrap design has changed over the years. The straps created a V across the guy's ass cheeks, unlike today where the straps go under guy's cheeks. I'd guess today's design is much more comfortable.
I love these pics. I saw them for the first time about a year ago. How awesome is it that all those guys not only had to wear jocks, but probably considered it the norm ( as it should be) and were proud to be military dudes in a jock.