I really like the Tier System set forth by Chad Ford. It gets past the tired "need versus best player" debate, or rather, it synthesizes the two and provides a framework for letting both interests play a role in a draft decision. There is also some specific discussion about the Hawks in the last third of the article, explaining how the tier system would have led Billy Knight to take Deron Williams in the now-infamous 2005 Draft.
Kudos aside, there are two problems with Ford's analysis of the Hawks. First, the major problem with the Williams pick is not so much that the Hawks took a player at an already-filled position (although there is some of that), but rather than the Hawks took a player who simply isn't as good as the two players picked after him. If Marvin was pouring in 20 ppg instead of 13, the criticism would be a lot less severe. Thus, the tiers are only as good as the scout who is deciding which playres go into which grouping.
Second, the Shelden Williams mistake was certainly not a result of Billy Knight taking the best player available. Rather, it was an overreaction to the mistake of ignoring need the past year. Knight was killed for not taking a point guard in 2005, so after he (correctly) identified the Hawks' problem as a lack of defensive rebounding and interior defense (the 2005-6 Hawks were a perfectly decent offensive team, but they were lousy defensively), he took the player who would address the need the best. The problem is that he again took a player who is inferior to the players taken after him. (Insert usual caveat that Marvin and Shelden are both young and could show improvement.)
The encouraging aspect for the Hawks is that they have two picks in the top 11 in a Draft in which there is consensus that there are 12 players in the top three tiers. Using Ford's framework, the Hawks will grab Mike Conley with the #3 pick since he is in tier two and answers a need (unless Knight thinks that PF is still a need in which case Al Horford or Brandan Wright will be the pick). The fact that the third tier players from which the Hawks will be drafting are all big guys indicates that Knight should go for the point guard with the first pick and then a PF or C with the second. I'll be overjoyed with Conley and Hawes if both fall to the Hawks. No, the late hour has not made me delirious; I really just used the words "overjoyed" and "Hawks" in the same sentence.