I'll do the best I can. It's not so cut and dry comparing some of the matchups. Take the Astros/Royals. They have their share of black players and some Dominicans, but also have their share of white players also.
The Astros have Cy Young candidate in Dallas Keuchel. They also have OF Colby Rasmus who has already hit 2 HR's in the series. Big Evan Gattis, 6'4 260 is the DH and also CF Jake Marisnick, 6'4 220. They also have a RF, George Springer, but I think he's mixed. So with the Astros you're going to have 4 to 4 1/2 white starters at any time.
The Royals are about the same mix, maybe one more white starter? You have 2B Zobrist, Hosmer at 1B, Moustakas at 3B, and Alex Gordon in LF. Not sure right off hand who their ace is on the mound, but they started Cueto whose Domincan today. So you also have 4-5 white starters on the Royals also. The Royals won today, so their series is tied 1-1. I'd say a toss up between these two.
Toronto and Texas a little more clear cut, although you have Josh Hamilton, Mitch Moreland and P Cole Hamels and Colby Lewis this team is loaded with Blacks and Dominicans.
Toronto however, has AL MVP candidate Josh Donaldson, SS Tulowitzki, 1B Justin Smoak, CF Pillar, 2B Goins and P R.A. Dickey. So when their not pitching their ace David Price, they could start as many as 6 white players. I would lean toward the Blue Jays, but it's not looking good. Texas just took a 2-0 series lead.
Like I said, I'll do the best that I can. If someone else has something to contribute, please do. I'll do the other 2 matchups later.
It's too bad the best two players in MLB are not in the postseason in Mike Trout and Bryce Harper!
In the other 2 matchups you have Chicago/ St. Louis. Chicago probably the whiter of the two, but it's close.
Chicago has the NL Cy Young candidate, probably will win it in Jake Arrieta and also Jon Lester. Also, 1B Rizzo, Big time rookie in LF/3B Bryant, RF Schwarber, LF Coghlan, and C Ross. So they will star 6 white players most of the time.
St. Louis has some big time pitching as well in Wacha, Lackey, and Lynn. Carpenter leads off at 3B, Piscotty and Reynolds will split time at 1B, Holiday who suffered an injury early on is back in LF, and Grichuk in RF. 2B Wong is Hawaiian, I think.
It's close between these two, but I'd give the nod to Chicago.
Now, the Dodgers and Mets. For LA it all starts with Pitchers, (3 time Cy Young winner Clayton Kershaw) and Zac Greinke. Seager is at SS, Turner 3B, Rookie Pederson in CF, and RF Ethier. Ellis who is white may split time with Yasmani Grandal who is Cuban at Catcher.
The Mets have pitchers, NL ROY Jacob de Grom, Harvey and Syndergaard. Also, Wright 3B, Murphy 2B, Duda 1b, d'Arnaud C, and Cuddyer in LF. Again it's close. It's virtually a toss up, but give the nod to the Mets.
Again, it's too bad we won't see Mike Trout nor Bryce Harper in the postseason!