We know Lonzo is a great team defender, not really a consistent stopper in iso but deadly in passing lanes and good with his anticipation. We know Caruso can genuinely be a stopper on the perimeter on reasonably sized guards. We know Williams will continue to be improve. That's a really nice start.

We also know DeRozan will almost certainly continue to be a bad-to-very-bad defender. And we know Vucevic will be a bad defender in space, although I can't imagine Billy would ever force him to switch, so it probably won't matter in the regular season as much, and he can probably be serviceable (and I think there's a chance Billy could straight up use Williams as a small ball 5 and switch everything at game's end against a lot of teams that may require switching).

So I think the overall regular season defensive ranking could definitely end up Top 10, provided that Zach stays locked in the way he looked this summer. It's going to be a lot harder to lock in like that during a random game against some middling NBA team on a Wednesday night vs. the Olympics, but if he takes that step and pushes to be a borderline All-Defense type of defender (which he absolutely has the physical tools to be), then the Bulls could honestly end up Top 8, maybe Top 6 defensively. The defense isn't really a concern for me.