You say Vujacic isn't better than Marvin, but I mean wasn' t he drafted like 30 picks later? The Lakers haven't had anywhere near the number of high picks the Hawks have had, so it's not a fair comparison anyway. BK was a pretty terrible drafter, there is no denying that. What happened is that he drafted Smith out of high school and Marvin after 1 year of college and eventually they turned into decent players so that when they finally got Horford after several blown picks (Shelden, Childress) they were able to get a good one in Horford and finally become relevant. He's not the worst ever probably, but there's a reason he doesn't have a job. The fact that Marvin is a decent player can't be counted as anything great either because he was the #2 pick taken ahead of some great players. His only real victory was Smith. Horford was kind of obvious, but at least he didn't screw it up.
Edit: Zaza was a pretty good pick too, but I still think he's way below average overall.