Agree. If you go to any island in the Caribbean where most people are West African descent you see random guys walking around the street that look crazy jacked. The same genetic pool in the U.S. has produced the fastest sprinters and top players in sports that require explosive power.
For sports like Strongman I think it's more about absolute size, and Nordic peoples are the world's tallest. If you're a 6' 9" basketball player, you can take enough steroids to fill out your frame, but you need the big frame to start with. If you're 5' 9" even with massively explosive genetics and chemically enhanced, you can't pack enough muscle onto your frame to compete with the guy who's 1 foot taller. And to produce a large population of maximally tall people, you need first world nutrition and healthcare.
But it's always been curious to me that black athletes don't dominate Olympic weightlifting. If you have a genetic advantage in relative strength and explosion, that's literally what Oly lifting is. Obviously it also takes years of training to perfect your technique and I suppose there's not really a large population of black athletes that pursue it.
Re. combat sports, IMO that's too much of a mixed bag to be any real indicator of genetic strength. We've seen many examples of top fighters and grapplers who compensated for poor explosiveness or relative strength. There's just too much skill, strategy and game planning involved.