I get Cressey's point about being careful about not overworking a kid so much that he gets hurt. Common sense has to apply for most parents and their sons to know when their arms need a break. Maybe that is in the Fall, or maybe that is in the months leading up to the High School season. Or maybe it is a month on and month off for awhile.
But I do not buy his point about only one player being "discovered" at a showcase. What is the definition of "discovered"? If that means a kid good enough to one day play MLB, then that may be the case. But there are thousands of kids out there with no aspirations to play professionally who want a chance to play in college and hopefully get some financial assistance. And plenty of those kids will NEVER be seen playing a game for their high school, so how do they get "discovered" otherwise?.
College baseball coaches have little to no chance to ever attend a high school baseball game--they conflict with their teams' seasons. Most universities have little to no money in the budget to go travel and see a kid. Some will rely on videos sent, but many want to see a kid play in the flesh, talk to them in person, etc. Stanford's pitching coach told us that he had seen exactly one kid pitch for his high school team during the past five years. And that is a high level D1 program--imagine what the lesser programs do to recruit players.
There seems to be a strong bias on this forum that showcases are a big money-maker for organizations like PG, Headfirst, etc. and the college coaches that work them. That may be the case, but if they were not worth it, they would die off quickly. How about the money saving benefits to parents and players? If there are 10 schools/coaches out of 30-50 working a camp and the player gets a chance to meet the coaches and play in front of them, how much time and money is saved by going to the showcase versus visits to even half of those schools? And how many would otherwise consider D2, D3, and NAIA schools without going to a showcase. Of course, should a player wind up with an offer of financial aid toward college, that would more than offset the cost of attending showcases and become a money-maker for the player and parents.
Yes, it makes sense to start small with a showcase or camp to get a sense if your son even has a chance of playing college ball. But don't be foolish and sit around and think your son is going to get noticed playing baseball if he takes much of the Summer and Fall off to rest. Unless he is a major talent with obvious tools, he may never get noticed.