What is Spring Redshirt Leagues/Teams? There is one in Socal called ABCL (Amateur Baseball Club League). I read an article about a college prospect opting out of high school baseball and playing on a Redshirt team.
The 2012 article below doesn't mention the red-shirt aspect of the ABC league, but college freshmen who were cut or red-shirted are also eligible. Basically an alternative for home schooled kids, academically ineligible kids, kids who were cut, kids who don't want to play for their HS team, full private school teams who don't want to be join a HS conference, etc.