Just one clarification ... there are no showcases at 12-U!
Anyhow, a lot depends on what the coach told the families when they came out for the team. Did he tell them they would earn pitching time or that they would each pitch 1/3 of the time or what? If there were no commitments, it sounds like there's a pretty significant difference between #1 and #2, and #2 and #3 ... 5 mph and more accuracy is a big difference at any age level, but especially at the younger ages. Even so, it's important at this level to develop all your players and to not burn out a #1 pitcher. I might expect something like #1 pitching about 45% of the time, #2 pitching 35% of the time, and #3 about 20%?