I give it an F. Not because I think we could have landed exceptional talent at any of the picks. Just because even if Justin James turns out to be as good as lets say, Danuel House of the Rockets, well it won't really matter because he's blocked by Buddy and Bogi.
The odds were in favor of picking someone more highly touted at 40 and nabbing James later on. The smart thing would have been to draft for areas of need since there isn't a whole lot of difference in the prospects at this point in the draft. If you draft someone like say Admiral Schofield and he turns out to be a solid backup, you've just gotten good value out of an invaluable asset. Instead you've kind of pigeon holed yourself into a situation where not only did you not fill any holes but even if the guy develops a bit, he's going to be blocked by players that are surely going to be better than him. So you're forced to either do nothing with him or play him out of position, making him even less valuable.
All in all, James and Guy are more than likely wasted picks and it doesn't have as much to do with whether they develop or not but solely based on their place on the team. Lets say Guy turns into a poor mans JJ Redick, well now you're going to have to have him out there in very specific situations defensively. The rest of the NBA is going toward versatile switchable players with size and the Kings are going for shooting without caring too much about how difficult it is to form a team around guys like him because he's so small and doesn't play the smallest position on the court.