#1 Willie Cauley-Stein
Willie Cauley-Stein was set to become a restricted free agent for the Kings, although after the 25-year-old expressed his desire to seek a new challenge the team reversed course on their initial decision and allowed Cauley-Stein to become an unrestricted free agent.
The center is coming off a season in which he averaged 11.9 points, 8.4 rebounds, and 2.4 assists in 81 games, and there is a belief that the lottery pick could still fulfil his early potential and establish himself as one of the league's better bigs.
The Kentucky product could also be available on a cheap deal as the majority of the NBA has already moved to secure their primary center targets. In terms of a fit on the Celtics, he's a much more rounded player than Kanter and the 7 foot big would present an exciting addition to Stevens' team this summer.