Boston.com's Marc J. Spears is reporting that Sam Cassell will soon become a free agent as the disgruntled point guard is expected to complete his buyout process with the Los Angeles Clippers as soon as this evening.  Cassell, who has been public with his desire to leave LA and play for a playoff contender, is expected to sign with the Celts once he clears waivers, which will take 48 hours after the buyout agreement is reached.  If all goes smoothly, Cassell could be wearing the Celtic green by Sunday. 

Casell, who's averaging just under 13 points and 5 assists per game, seems to be the missing piece to the Celtics' playoff picture.  He will provide a veteran presence at the backup point guard position and will no doubt see a significant amount of time playing behind Rajon Rondo.  Rondo's play this season has been much better than even his biggest supporters could have hoped for, but he seems to have trouble matching up against bigger and better point guards.  Hopefully this is something that Cassell, a 38-year-old veteran of 15 seasons, can help improve on.