From where I sit, there is truth to both sides.
When I covered A ball, I saw plenty of guys who hit .198 and moved up while guys who hit .298 got released. I saw free agents who performed better on games than draftees lose ground and then lose their spot. Why? Because the guy hitting .198 was learning to overcome one fatal flaw and the guy hitting .298 was playing to his potential.
It doesn't seem fair and. sometimes, it doesn't seem right. But if 5 guys from a New York-Penn League team make it to the major leagues, that was an incredibly successful team, even though it went 20-56. Meanwhile, 1 guy from the league championship team makes it.
Over-simplification? Perhaps. But closer to reality than most can possibly imagine.
I think we all can agree the draft is a terribly subjective process.It's all about age, size and learning curve, not necessarily about results.
In the end, both camps are right. Not many players are missed, because part is self-fulfilling prophecy and part the odds to begin with.
The only inevitable truth is that the truly athletic, talented AND hard-working player makes it. After that, anything goes.