According to this article on mlb.com, pitcher Ted Lilly has a wrestling background of some kind (though, outside of this article, I've read nothing else about him wrestling in high school).
http://mlb.mlb.com/news/article.jsp?ymd=20100210&content_id=8048648&vkey=news_chc&fext=.jsp&c_id=chc
Former Philadelphia Phillies catcher Darren Daulton was a state champion wrestler in high school.
There might be several reasons why it's hard to find well known baseball players who are former wrestlers. In states which produce the majority of MLB players--California, Arizona, Texas, Georgia, Florida--many top baseball prospects focus on baseball year round. They spend their winters getting ready for baseball instead of wrestling or playing basketball.
Also, wrestling simply isn't as big in those 5 states as it is elsewhere in the country. The states with the highest percentage of male high school athletes participating in wrestling are Alaska (11.5%), Nevada (10.9%), Wyoming (10.6%), Utah (9.8%) and Nebraska (9.7%). Though Nevada is emerging as a baseball talent pool, those states do not produce many professional baseball players. By comparison, California ranks 33rd with 6.2% of male high school athletes participating in wrestling; Florida 34th with 6.1% and Texas 49th with 1.7%. The only state with a lower percentage than Texas is Mississippi, which is the only state that doesn't officially have high school wrestling.
Wrestling is a great sport so I hope you can encourage more baseball players, and athletes from other sports, to give it a try!
