I have been surprised to see how many of my 2017-8 son's friends/acquaintances who have gone D1 are either not playing or have already transferred out of their school, and usually to a lesser situation. Also know of a guy who went to a JUCO, and has already transferred to a top 25 program after one GREAT fall season. The attrition seems worse, the better the school is baseball wise. I think that the Big 10 schools might hold on to players a bit longer than the other P5 conferences, but I don't have any data to back that up.
Know another coupla kids who are killing it in mid majors...one threw over 80 innings. Who cares if you are at a great program if your ass is on the bench?