Celtics have a tough decision to make on big man's future

Luke Kornet is an unrestricted free agent this summer. As the Boston Celtics' third-string big man, he played an important part in their championship rotation. 

His size, defense and movement make him an enticing low-cost prospect for front offices around the NBA. Boston may struggle to retain his services if other teams extend offer sheets.

"Boston has full Bird rights on Kornet if it needs to give him a slight raise on the $2.4 million he made a year ago as a sometimes-rotation center," The Athletic's John Hollinger wrote. "He may have fans in other front offices willing to pay more, however, and ... the Celtics’ luxury tax situation likely limits how high they can go."

Boston has multiple bigs on its bench. Kornet, Xavier Tillman and Neemias Queta could all hit free agency this summer. Tillman is an unrestricted free agent, and Boston holds a team option on Queta. Kornet has been the most consistent out of those three bigs, playing in 63 regular season games and making 13 postseason appearances.

As a second-apron luxury tax team, the Celtics are limited in the contracts they can offer free agents. However, Boston holds Bird rights for Kornet and Tillman. The Celtics can go over the tax restrictions to keep one or both of their veteran bigs. Yet, it's unlikely they will move to retain both talents. 

Tillman provides far more defensive versatility than Kornet. He can switch multiple positions, he is physical enough to bother opposing bigs and he can play at the level of the screen. Boston must decide if it values Kornet's size or Tillman's overall versatility heading into next season.

Of course, both bigs are now negotiating from a position of power. They're both NBA champions, although Kornet played a much larger role in that success. 

Boston has a tough decision to make. Kornet has been a valued part of the rotation since Joe Mazzulla took over as head coach. Brad Stevens is a fan. However, if his market has grown, and his production doesn't match the tax implications of re-signing him, it's likely he will land on a new team this summer.

Brad Stevens has his work cut out for him over the next month.