Lets say we are talking about the top 33% or about 100 baseball teams. That is 3500 players from across the nation who qualify. I am guessing that less than half of that amount plays so we are talking about 1700 players. Of that amount, 3/4ths of them are sophmores, juniors, and seniors. Thus, for the 400 or so freshmen players who may qualify for the top 100 teams in a given year, the vast amount of their competition are older, stronger, and wiser. Looking back, it is a daunting challenge. The upside can be unbelievably rewarding, but it may take years in some cases to realize that.
At the top, it is no longer a local or state competition for playing time among star players. As Prepster points out, it is a national competition for very few precious spots. Of the lucky ones who are even called, far fewer than that actually get to serve.