One way of looking at it:
- A top 3 pick should get you an All-Star, otherwise he is a bust
- A top 9-10 pick should get you a starting 5 player, otherwise he is a bust (150 starters in the NBA, average career, say, 16 years, so each draft should yield 9-10 starting caliber players to replace the retiring ones)
- A top 15-17 pick should get you a rotation-quality player (similar logic to the above assuming 8-9 players in regular rotations per NBA team)
So, whether Obi is a bust depends on whether you view him as a starting power forward for an NBA team. The jury is still out on that. Can he hold the starting PF position on the Knicks? Depends on what the Knicks' aspirations are. He can definitely be a starter, or even a top 2 or 3 player on the Knicks if they are a perrenial bottom-dweller. So, from that perspective he is not a bust. He might also be a plug at PF on a starting unit with multiple stars at other positions, though I do not see a path towards that scenario in the near term. He does not on his own elevate the team towards contention, but, once again, that would be the expectation for a top 3 pick.
All in all: no, I am not yet ready to pronounce him a bust, given where he was picked.
Also, worthwhile to consider the complete context of how Obi was picked over Haliburton:
- Randle at that time had been written off as a free agent bust for the Knicks, people had him penciled as good as gone (spinovers, etc.)
- Ntilikina still held a promise as a potentially serviceable point guard due to his youth, defense and team-first attitude, picking Hali would have pushed him down on the depth chart
- The team had no offensive go-to threat, and Obi was seen as potentially being able to provide just that, plus size, to the extent that he was bandied around as a potential top 5 or even top 3 pick
I am not saying the above considerations were 100% solid, in fact, I myself would have preferred Hali (though I thought he would be gone by #6), but must admit that at the time those arguments made sense. Drafting is a game of chance, any way you cut it, any draft moves are just guesses by definition.