Chris Rock, while not exactly stupid, has been educated far beyond his intellect.
Baseball does business in two countries. The USA and Canada. The USA is about 13% black. Canada, which is one-tenth the size is 3% black. That works out to about 11.5% black between the two countries it does business in. Baseball is 8.5% black (here note that "black" means non-Hispanic black). 8.5% of the players, 11.5% of the market. Not that bad really. If this were a quota system, baseball needs about 13 more USA/Canadian blacks to be "even".
And if you wanted to have a quota system, the under-represented group? Umm, Chris, that would be white non-Hispanic people. Who make up about 77% of the combined population of the USA and Canada, yet only about 55% of MLB players.
But, of course, baseball draws players not just from the USA and Canada. It draws from all the baseball playing countries. The ex-Spanish (and the still Dutch) Caribbean. The ex-Spanish parts of the North American mainland (Mexico and Central America), the northern rim of ex-Spanish South America (mostly Venezuela and also Columbia) ; and from baseball playing nations in Asia (Japan, South Korea and Taiwan). With a few wild card players from Australia, and there are now some minor leaguers from the cricket playing nations trying to convert to baseball, because of the $$ involved.
And the %age of American and Canadian blacks who live in those countries is, umm, well, zero. (Note here that many Latin players are black, but none are "African American"
(and note that my, and Mr. Rock's accounting, as MLB's official stats, make that distinction.) And there are more people living in those countries than live in the USA and Canada. Almost three times as many. That means 8% of baseball players in the Majors are black (non-Hispanic black people born in the USA or Canada) while less than 4% of the potential talent pool is. Thus blacks are over-represented in MLB, as a %age of the potential talent pool, as they are in the NBA and NFL. Latins, both those born elsewhere and those born in the USA, are "over represented".
Of course that only matters if you look at people through the prism of color, as Mr. Rock and his ilk do. I only see one color. Red. Cincinnati Red.