The "no defense in the NBA" myth is completely baffling to me. It couldn't be the furthest thing from the truth. These are professionals we're talking about. And draft prospects have almost exclusively been narrowed to guys with the necessary length and quickness to defend.
For what other reason would Luka even be doubted as a prospective player in the league? Defense is the ONLY reason he is doubted. So it must be something that is highly valued as a NECESSITY in today's game. Doesn't matter that Luka plays below the rim. There are plenty of guys like that in the league. What matters is his ability to defend ball-screen action. Either by switching and containing a guard on the perimeter. Or by helping on the screen and rotating back to his man. Switching is pretty much out. It's just too big of a quickness desparity. And for whatever reason, Luka hasn't helped and recovered in ball-screen action as well this season as he did last. He was at least taking better containment angles last season and that's something that can be easily corrected.
But at best, Luka is still a bit of a clunky defender. As of today he absolutely would be exploited in the modern spacing and ball-screeing rich league, and couldn't competitively be on the court.
Quickness is almost impossible to develop, but Luka is the last person I would ever doubt. He will put in the work to once again transform his body. He will max out his quickness and give himself every chance of becoming a capable defender to stick in the NBA