"In the professional level, the coaches were always making suggestions, doing advanced drills, helping in cages, and breaking down each individual's mechanics in order to make adjustments and corrections."
Shep, with all the items being discussed, I wanted to make sure this point you made is not overlooked. While I don't know that this is unniversally true, in fact some information suggests it is not, professional baseball does have extremely good teachers/player development coaches. I have mentioned several times how I watched a hitting coach completely rework the swings of two players last summer. In mid June, both were struggling below .200. With one, he worked daily, for hours on end, to shorten the swing and make it more direct to the ball. It took over one month to make the adjustment. Improved both the average and power numbers significantly and the player is now in AA. For the other, the coach worked on keeping the bat through the hitting zone longer. Player ended up hitting almost .350 for the last 2 1/2 months of the season with terrific power. Unfortunately, he has not recaptured that swing this season and seems unable to get similar assistance to reaquire the magic.
In his first Spring Training, our son had some opportunities to talk hitting with Dwayne Murphy, the former Oakland A's centerfielder, and took every oppotunity to do it. It was invaluable to hear and learn from someone he knew could really play the game. Helped him immensely adjust his approach at the professional level, perhaps, more mentally than physically.
There is little doubt that players can improve on the field at a much more prolific pace in professional as compared to college baseball. That should never be doubted or mistaken, or lost in this thread about the impact of the "business of baseball" and dealing with its off the field ramifications.