I think it's fair to conclude that Josh Jackson probably would have underperformed a top 5 draft selection regardless of which team drafted him.
Great prospects find a way to show out, even on bad teams. Devin Booker, after all, has managed to look like he at least has potential to become a really valuable offensive player some day (his stats currently, one presumes, are fairly empty).
That said, I don't think you can entirely discount the effect on a player of being drafted by an organization that is truly awful at developing young players.
I would say that both Bender and Josh Jackson were drafted too high, yet at the same time I believe pretty strongly that if they'd been drafted to better situations, they would probably have shown a lot more potential to be useful NBA players, by now.
I think Justise Winslow is a good reference point. Was he a good top 10 pick? Not really.
He's had a rough transition to the pros and has been, overall, fairly disappointing.
If he'd been drafted by the Suns, he might be struggling just as much as Bender or Josh Jackson.
Yet because he was drafted by a team coached by Spoelstra, he's been able to carve out a decent role and got an okay second contract.