Baseball obviously has high popularity in a substantial number of non-US countries, though the main ones that feed the MLB (the DR, Venezuela, and Cuba) aren't often top-of-mind countries for many. The Japan/Korea interest is obviously non-trivial too.

Basketball is the obvious one you're leaving out that's about the same age as Volleyball (itself a US team sport), and probably has the most international popularity -- especially if just going by people-counting since China alone is an enormous market.

Funny thing, though: US players make up about 73% of the MLB but about 78% of the NBA, despite the NBA having more international popularity, and the current best players in both being from non-US countries.