I think you're being purposely obtuse on this point. The decisions a GM makes in who to draft, which trades to make (or not make), how to spend money on free agents are not at all random chance events. They are decisions. Decisions made by that particular GM that either improve the team or don't. Not being able to say whether or not Vlade is a good GM is different from the pseudo nihilistic approach of "who cares who is in charge it's all completely random". Vlade Divac is in charge.
You've taken the stance that hiring a first time NBA GM is a disastrous move on par with hang gliding off Mt. Whitney with no prior hang gliding experience and my point is simply that every GM was once a first time GM and that unlike hang gliding or piloting or captaining the Titanic or whatever other metaphor you want to use, there is NO specific training that will ensure that you acquire the skills to become a good GM. Either you can recognize talent or you can't. Either you know how to build a team or you don't.
Personally I wanted Ranadive to keep Petrie on, at least for a year. A new owner, taking over just before the draft with a coach already hired? It made sense to keep some continuity, especially since Petrie has seemingly always been able to work with different head coaches. Instead he hired a first time GM who wasn't on the same page as his head coach. And so far D'Alessandro's track record as a GM isn't great. Will Vlade be better? I don't know. Neither do you.
But here's the more important question - what GM with lots of NBA experience and a good track record is available as an alternative? Would you honestly rather have Chris Wallace. Chris Mullin, Mike Dunleavy or David Kahn just because they have NBA experience and Divac doesn't? Keep in mind, those were the names tossed out when the Kings were looking for a new GM along with inexperienced guys like PDA, Kenny Smith, Travis Schlenk and guys who quickly stated they had no interest in the job in Phil Jackson, R.C. Buford, and Larry Bird.
So who is the guy that you think should be in that chair instead?