Deals are judged by the comparable ones of others, and the obvious and necessary comparison here is with Paul Millsap, Jefferson's running mate as recently as five months ago. Millsap signed with Atlanta for two thirds of what Jefferson did ($9.5 million annual compared to $13.5 million for Al), and for two thirds of the time (two years instead of three). Logically, this would suggest Millsap is two third of the player. But he's not. Without wanting or needing to fully compare the two, we can all hopefully concede that they are about the same, give or take. But the price is very different.
Millsap is signed to an amount comparable to his talent, for shorter time. He provides Atlanta with the talent boost that will keep them out of the cellar - if you want bums on seats, you need that - and his contract makes him extremely tradeable. Millsap is a valued commodity around the league as a quality, versatile, two-way role player, and by getting him at the right price, Atlanta put themselves in a position to take advantage of that. And until they do, he'll help them significantly as a player.
Charlotte, however have paid the 'Bobcats tax' and will suffer for it. Jefferson is, at best, at the very top end of the acceptable overpay range, and probably slightly beyond it. Yet it is that third year that makes it extremely difficult to trade him before the summer of 2015. Rebuilding teams need as much flexibility as possible - with his undervalued, very competitively priced skills and short contract, Millsap could be traded for a quality return as soon as February. Jefferson can't. He costs too much and he's under contract for too long to be highly prized. Indeed, he may not be tradeable at all. This is not all bad, as it will mean a quality player will stay with them for three years.
At some point, a rebuilding project needs to involve actual building. At some point, you need to start acquiring quality - you can't forgo all talent acquisition just to stay bad just to hopefully get lucky in a good draft class. Charlotte have reached that point. Atlanta have somewhat, too. But in these respective signings, the Hawks and Bobcats have put themselves in far different positions. One team landed a quality player on a great price who will help the team in both the immediate future and (via trade), likely the long term. Meanwhile, Charlotte spend $21.5 million more to achieve less.
It was the right idea, but not the right execution.