Just to play Devil's advocate here, high-level volleyball players tend to be extremely tall. The average male pro/olympic player is anywhere from 6'6" to 6'10". Some are, of course, even taller.

There are well-known correlations between height/weight and lifespan, see e.g.: https://pubmed.ncbi.nlm.nih.gov/1600586/

So it's not prima facie a foolish notion that high-level (pro/olympic-tier) male volleyball players suffer from a ~5-year reduced lifespan relative to a much smaller population.

I've seen papers that are a hell of a lot worse, that's for sure.

As volleyball is a sport for the disadvantaged, this critique is the definition of punching down.

I feel like this is par for any random paper. Never trust any conclusion's take on correlation vs causation.