No the gene pool didn't dry up at all Skimpy.....Want to know the reason why there are fewer "home grown" US athletes playing baseball, but playing basketball or football. It's really very simple.
You have a lot of former (Elway for just one) players and current players who were excellent baseball players and who could have had a shot at the ML, but chose either football or basketball because they can make millions right away out of college or high school and not have to go through 3,4,5 years of minor league baseball before they get to the ML, if they get there at all.
How many come out of college, sign for the big big bucks in the NBA and NFL right away and wind up being a bust in either league? Quite a few, but they have made their "big" money and didn't have to ride buses, play in small ballparks, live in cheap hotels or motels, eat at fast food places and hope they could make it to the ML.....The NFL and NBA pay the big money right away everything is first class, no waiting several years.
That is the main reason, there is more talent coming from the Latin countries, Japan, Europe, S. America and elsewhere.......Our "homegrown" talent for the most part, don't have the patience to hone their baseball skills in the minors....They want it and they want it NOW and the NFL and NBA give them that.