If we assume the Hawks are going to improve due to the continued development of the young guys due to the fact they are under 25, then doesn't Cleveland (is Lebron 25 yet?), Orlando (Dwight is the same age as Al/Josh/Marvin, maybe development from Gortat and Anderson too) and Boston (Rondo also same age as Al/Josh/Marvin, plus Big Babby, if he returns, and Perkins) get a bump from continued development of their "young" guys?
In the end, I do think the Hawks have the most to gain from the development of their young players (how much better can LeBron and Dwight get), but they also have the most improvement to make as a team to crack the top 3 - there was a significant gap between those three and the Hawks last year. That being said, injuries will likely be the deciding factor.