Is it the suit or the color
 

On these boys speedos that leaves there crotch more prominent?
Shadow of the light striking them?

I don't think it has anything to do with the color of their suits or the way the light/shadow is hitting them. Their bulge is definitely more prominent but that is probably due to how thick the suit material is. The thinner the fabric (or if it doesn't have a lining), the more "detail" you see.

I am guessing color and material. Plus they are probably practice suits so they have thinned out from the chlorine. Nice looking guys, too.

My guess
 

I am guessing it is simply the size of his balls. All of them are wearing the same.

is it the suit or the color
 

I think both the fit of the suit and color tell how one likes their speedos. I find wearing bright colored speedo style briefs that fit nice being well lined and snug with good material are the best ones, especially Speedo or Arena brands, feel great and more so when wet and not in a hurry stripping them off.

Just happy to see the photographer is my guess.

I think the material may be a bit thinner than other suits, but the shadow or side-lighting helps accentuate their 'maleness'.

These guys are hot. Thanks for sharing. They all have nice bulges.

It's the ends of the season, they've won the league and worn out their team suits leaving the fabric thin strained, maybe.

I think it's a combination of color and thinness of the material and the light. That's pretty harsh light, direct sun from the side/above. Flatter, diffused forward light would hide the details, and darker material would too.