I really don't have a problem with guys not reaching their pre-draft projections. Most of us know (or for good reason, have never heard of) Shawn Abner, David Clyde, Matt Bush, Joe Borchard, Clint Hurdle, Dewon Brazelton, Billy Beane, Colt Griffin, Ryan Harvey, Mike Kelly, Bryan Bullington, Brady Aiken, Mickey Moniak - highly touted first round MLB picks who never came close to their "projections".
The problem I have is that, with the exception of the rare DITR, you have little chance of getting a future ML contributor beyond the 3rd or 4th round, and almost no chance of getting a guy who will be an All-Star, much less a HOFer. Here's a short list of guys who were picked in the 5th round or later in the MLB draft: Tim Hudson, Wade Boggs, Jim Edmonds, Fred McGriff, Goose Gossage, Andre Dawson, Nolan Ryan, Albert Pujols, Jim Thome, James Shields, Kenny Lofton, Orel Hershiser, Bret Saberhagen, Don Mattingly, Ryne Sandberg, Jeff Kent, John Smoltz, Andy Pettite, Roy Oswalt, Kyle Lohse, Kevin Kiermaier, Mark Buehrle, Mike Piazza.
For the first couple of rounds, there should be very little difference between a team that spends $0 on scouting and $20M in scouting. Anybody reading Baseball America or any of a hundred baseball websites can draft Steven Strasburg, Bryce Harper, Gerrit Cole, Manny Machado, Anthony Rendon. But, when you get beyond the top 100 or so players, that's where scouting ought to make a difference and I see no evidence that it does.