I gave Kessler a lot of (justified) crap last season, but the fact remains that he's the only young player on this team who has an elite NBA skill (rim protection).
Think about that for a moment.
No, a player doesn't have to be "ready" at this point. But if you're going to be a building block, you need to have the type of raw talent that, when polished by experience and reps, can make you elite at least in one area. For instance, I don't see any of that in Keyonte, and he's the guy they're trying hard to push as the "face" of the team. He's either bad or mediocre at everything he does. Athleticism, shooting, ball handling, decision making, facilitating, defense, effort. So far, overall he looks like an NBA bench player, but has a ridiculously inflated role and usage on this team for obvious reasons.
I repeat: he doesn't have to be ready. But the trouble is that from day one, he's looked like he probably just isn't talented enough for the type of role the Jazz seem to have in mind for him in the long run. They're squinting hard.