After increasing their regular season win totals for six straight years, the Atlanta Hawks plateaued last season. They slipped from 53 wins to 46, losing in the second round of the playoffs for the third consecutive year.

With Joe Johnson due over $100 million in the next five years, they have almost no room to maneuver under the salary cap, even if they don’t re-sign Jamal Crawford. Most of their roster is either similarly overpaid -- Kirk Hinrich, Marvin Williams -- or too young to have much trade value -- Jeff Teague. As a result, the team only has two attractive trade pieces: Al Horford and Josh Smith, two athletic 6’9+ forwards in the prime of their careers.

But while Horford has two All-Star appearances to Smith’s none, Smith is the player the Hawks should try to keep. Neither is capable of playing center for an elite team, and Smith is a better individual defender and a more dangerous offensive player.

Horford has been a small-ball center for most of his career, but after Dwight Howard and the Magic annihilated the Hawks in a four-game sweep in the 2010 playoffs, the Hawks began starting Jason Collins, a 7’0 defensive stalwart, when they faced Orlando. Even if they can avoid Howard in the future, a front-court of the 6’10 Horford and 6’9 Smith would be severely undersized against teams like the Bulls, Lakers and Mavericks, who can play multiple seven-footers.

Horford’s two strengths (rebounding the ball and spreading the court) aren’t nearly as valuable at the power forward position as they are as a center. While Smith isn’t the shooter Horford is, his usage rating is five points higher, indicating that Horford depends a lot more on other’s creating open looks for him.

Smith, meanwhile, has quietly become one of the better passing forwards in the NBA: averaging 3.9 assists per 2.45 turnovers over the last two seasons. Among front-court players with the ball in their hands as much as Smith, only a handful (Hedo Turkoglu, Lamar Odom, Pau Gasol, Boris Diaw, Tim Duncan) have a higher assist to turnover ratio over the last two years.

Defensively, Smith is still one of the elite athletes in the league. Both players have wingspans of 7’0 but Smith is the more explosive leaper, which explains why he’s been a consistently better shot-blocker than Horford over his entire career.

Long-term, if the Hawks keep Horford at the power forward position, they will need to find a center who can create his own shot and allow Horford to spot up off of him, much as he did with Joakim Noah in college. Needless to say, the only way to find a center capable of doing that is in the top-5 of the draft.

In contrast, Smith’s ideal front-court partner would be a seven-footer who could defend the post and stretch the floor. That’s a much easier player to find -- Mehmet Okur, Roy Hibbert -- than a center who can score from the low block or create off the dribble.

Against most of the NBA, Horford is an effective center. But for the Hawks to advance past their second-round plateau, they’ll need to get bigger in the middle, and finding a seven-footer who can complement Smith will be a lot easier than finding one who can complement Horford.