It’s no secret the Celtics have a serious question mark at the center position entering free agency. Boston’s best two remaining centers are free agents (Al Horford and Luke Kornet) and its starting center (Kristaps Porzingis) was dealt away to the Atlanta Hawks this week in a move to trim salary.

The Celtics would love to retain the big man, but he could be looking for more money than they are willing to pay.

But keeping Kornet is looking less and less likely. According to veteran reporter Marc Stein, Kornet is being eyed as a potential free-agent signing by the Spurs, who could use their full mid-level exception--$14.1 million--to secure his services. The Celtics just can't afford that.