MLB scouts are EVERYWHERE. Anyone that selects a college because an inherent UNIQUE "exposure" are living in the 19th century. Transportation and communication technology have changed scouting, as evidenced by the various talent "rating systems" available on your PC.
Don't get me wrong, the "power rating" of conferences has reasonable validity and impact upon player performance #'s, but that in itself does NOT preclude a player from having the opportunity to play MLB.
As MSREASON stated, the PRIMARY goal of a college athlete should be to get their degree. Too many YOUNG & INEXPERIENCED athletes bite at the 1st worm on the hook, with many never establishing reasonable goals BEYOND sports. College is an OPPORTUNITY of a lifetime and should be cherished far above a "bird dog" signing bonus that'll generally blow out the window in a couple years.
The MLB Draft in itself gives credibility to the coach more than the "program." If you want program credibility, your post-season record is viable evidence. As long as MLB keeps tampering with collegiate rosters, colleges will NEVER maximize their potential.
According to your logic, the "power base" of a collegiate program should be based on frosh & sophs. Did you ever think of WHY this pattern has developed? Because of roster instability and threat of MLB.