Who is the Celtics' best free agent signing of all time?

In the rich and glorious tradition of the Boston Celtics, where they have won the most NBA titles in league history, it may come as a surprise as to how subpar the franchise's ability has been to acquire a top free agent.  I had the discussion recently and it seems all the Celtics' top players of all time were acquired via a trade or the draft.

In researching the candidates, I basically found a lot of guys that either didn't lead them to anything relevant or were only around for 1 season of the title-run.  It's amazing that in their history the Celtics have never landed a big-time player via free agency, a clear-cut top 20 guy in the league at the time.  It's even more amazing how there's no one worth mentioning between 1995 and 2007 (could this have anything to do with the Buffoon or Evil Emperor?)

Free agency hasn't been around that long so let's take a look back at the marquee guys Boston inked and vote in the poll who was the best ever.

Derek Smith, 1990.  Was a prolific scorer when he was younger playing with the Clippers and a key rotation guy on the 1990 Atlantic Divison Champ Sixers.  Helped the Celtics' immensely in winning their' rugged first round series vs the Pacers in 91 but only played 2 regular season games, and retired at year's end.  His tragic passing is often forgotten about.

Xavier McDaniel, 1992.  The X-Man was coveted by Boston back in the late 80s but they could never find a way to acquire him until he became a free agent in September of 92, coincidentally one month after Larry Bird retired.  I distinctly recall McDaniel telling the reporters he wasn't there to "replace Bird" (wise-words).  He'd stick around in Boston through the 1995 season.

Dominique Wilkins, 1994.  Nique was everything the Celtics wanted but was at the wrong age when Boston inked him during the summer of 94.  He'd help lead the team to the playoffs as an 8th seed where they gave the top seed Magic a scare of a lifetime before bowing out in the first round and closing the Boston Garden permanently.

Dana Barros, 1995.  This was one that definitely had potential as Barros came off an all-star season in Philadelphia in 1995.  However when he arrived in Boston it was obvious that his stellar play in Philly was more due to John Lucas running a lot of plays for him.  Barros had a hard time getting playing time in Boston, basically sharing duties with Dee Brown and David Wesley while he was there and never reached the production level he had while with the 76ers.

James Posey, 2007.  Signed for the veteran's minimum and just for a season, as he'd leave after the 2008 title run.  He was the Celtics' 6th man during that great run and a do-everything-type of guy. 

Eddie House, 2007.  Signed to be one of the main guys off the bench and played his role to perfection in helping win the title in 2008.  He'd actually stick around until the 2010 trade deadline when he was moved for Nate Robinson.

Sam Cassell, 2008. Signed mid-season to give the Celtics more of a sure-thing at the point backing up Rondo. He'd play sporadically, also taking minutes from Eddie House.  But it all worked out in the end so no one cared.  (He'd actually be on them for half the 2009 season, dressing almost every game but never playing in one until he was shipped to make room for Mikki Moore.  Cassell even got two techs in one of those games from the bench and was ejected, although this doesn't show up on his basketball-reference page.)

PJ Brown, 2008.  Signed right along with Cassell.  His tough-defense and rebounding was important throughout the playoffs and who could forget his enormous Game 7 shot vs Cleveland, the biggest shot of his career and likely that entire Celtics' title run.

Rasheed Wallace, 2009.  Signed to give the Celtics depth. Wound up mailing in the season with a lackluster performance which consisted of him shooting (and missing) a lot of 3s.  Seemed to exert more energy in the playoffs and was on the team that lost Game 7 of the finals that year.  Many people blamed Rasheed Wallace for everything bad with the Celtics that year.

So who do you consider the Celtics' best free agent signing of all-time?  Did I miss anyone? I was contemplating including Pervis Ellison in it but figured he didn't deserve to be because after his injury in Washington, he never played at that level again.  I didn't include Artis Gilmore, Shaq, Jermaine O'Neal, Delonte or Marquis Daniels, so maybe I should've kept Rasheed out of it too.  But by mentioning Rasheed I felt it gives people another chance to blame him for something :D

I think it will come down to your definition of "best" as in "do you mean best player in the league at the time or "the guy helped lead us to a title and played for a low salary" or  some combination thereof.  This was my thinking actually and after a lot of deliberation, I narrowed it down to McDaniel, Wilkins and Posey.  And I selected...James Posey.  McDaniel was still basically in his prime and is unquestionably a better all-time player than Posey.  Dominique was the biggest name of all but he was coming towards the close of a hall-of-fame career.  But McDaniel joined back when the Celtics were still selling the glory of the 80s (albeit the last remnants).  Wilkins was somehow won over by ML Carr's vision and convinced to come along.  But Posey went in 2007, long after the 80s and decided to embrace the cold to become the glue-guy on a championship team.

Was it predominantly because KG and Ray Allen had just been acquired?  And didn't he only stick around one season?  Yes but he came aboard nonetheless and was a pivotal guy on a title team.  That means the world to me personally.

Explain why in the comments on who you pick and if you select "Other" you better tell me who!