I disagree with the meme - if Kelly + 16 were worth the 8th, it would have been done a long time ago.
1. Drafting is very player dependent. It depends on WHO is available at the #8 pick.
Consider the players taken at #8 in the draft in the past 30 years. How many of those turned into star players?
Out of the following list of 8th overall picks, I would say -- Rudy Gay, Andre Miller, Vin Baker (before he succumbed to alchoholism), Detleft Schrempf, and Ron Harper. That's 5 all-star level players in 30 years? Not very good odds.
http://www.mynbadraft.com/nba-draft-picks/8th-overall/80509/2. I feel that Kelly + #16 for the #8 pick is an overpay. Kelly has already experienced two years of development and shown that he has at least been worth the #13 pick where he was taken. A rookie taken at #8 will be very raw, and even if he isn't a BUST, will take another 2-3 years of development before you could even consider him ready to contribute.
In other words there is a 'time cost of development' for rookie prospects that posters fail to consider. Even IF the draft pick is a success, and everything you hoped for, that guy won't be ready to impact the team, most likely until his 3rd year in the league.When you talk about trading guys like Olynyk, Bradley, and Sullinger, you have to consider that they have all been developed at least 2-3 years already and are just about to hit their prime. Trading one of these guys will set you back 2-3 years, so that even if the guy you get back with the draft pick is an upgrade, you have to wait around that amount of time before you see return on your investment.