That's incorrect, btw. Hispanics made up 31% of MLB players in 2017 as you can see here, that didn't go up 19% in two years.
http://nebula.wsimg.com/2b20e1bb7ea...3A56D8FB782449D2A&disposition=0&alloworigin=1
Not everything is 100% social status, although I admit a large part of it is. Why are MLB pitchers predominantly white? There are definitely differences in physical makeup between different races, that can't be argued. Caucasian males average 5'9", Hispanic males average 5'7". Height is shown to be conducive to both velocity and more obtuse pitch angles. Is that why? I haven't done a study on it. But there's enough to say that physical differences might play some small part, how ever minute.
I'm not arguing the point about the effect of economic opportunities (or lack thereof) at all. I'm just arguing it on face value. Name me a basketball team in the last 20 years with 17 white kids out of 20 that's contended. Data tells us it isn't going to be successful historically, for whatever reason you want to argue.