Well, here's an alternate theory: As a fifth-year senior, Gillis doesn't need the training that the freshmen need, and in fact, his role in practice is to help train them. That doesn't mean he'll have the exact same role in actual games.
Look, I'm not saying that you're definitively wrong, and I've never argued that Mason will be a "15+ minute per game player". What I'm mostly saying is that you are the one being awfully definitive when we have seen two intrasquad sessions and still have nearly two weeks before we see these guys play an exhibition game against even a lousy team, nearly three weeks until we see them in an exhibition against a team that's actually good, nearly a month until we see them in a game that matters, and more than a month until we see them in a game that matters against a team that's actually good.
It's a little early to be that adamant, don't you think?