Question: What were the %s (approximate) of college and HS baseball players taken in the first 10 rounds of the MLB draft this year?
Answer: 75% college, 25% HS
Bonus Questions: What were the %s (approximate) 10 years ago? 20 years ago?
Answers: 65% College, 35% HS; 50% college, 50% HS
What’s driving this? Statistical analysis (Moneyball) and $.
Here’s a link to a good Baseball America article containing that data and more.