The deal, which had been rumored for some time when an early version fo the deal fell through at the 2007 NBA Draft, finally came to fruition on this date in 2007, and netted Garnett's former team - the Minnesota Timberwolves - Al Jefferson, Ryan Gomes, Sebastian Telfair, Theo Ratliff, Gerald Green, cash, Boston's own 2009 first-round pick, and the 2009 first-round pick Minnesota traded to Boston in the 2006 Ricky Davis-Wally Szczerbiak deal.
Garnett agreed to an extension in addition to the two years remaining on the contract he was then on, inking him until 2011-12, and had been instrumental in blocking the earlier attempt to trade for him. This change of heart had everything to do with Danny Ainge bringing Ray Allen to Boston, who, along with Glen "Big Baby" Davis were traded to the team from the Seattle Supersonics weeks before this deal was completed that summer. Garnett had his agent, Andy Miller, send a back-channel message that he would have opted out of the final year of his current contract if no other major names were added to the roster before the deal was completed, effectively making him a one-year rental.
We all have the benefit of history on our side regarding what happened next, with Ainge managing to bring Allen into the fold, changing the view of Garnett, and setting the stage for Banner 17 the following spring. But, it was almost derailed by the Big Ticket becoming a Los Angeles Laker. This is not the kind of alternate history I enjoy, but it nearly did go down. Here's an except of a conversation on exactly that near-miss between Miller, Phil Jackson and Glen Taylor, owner of the Timberwolves (per NBC's Sean Highkin):
"Phil Jackson: Dr. [Jerry] Buss came to me and said, “I have a handshake agreement with Taylor, that he’s going to come to L.A. But [Kevin] McHale hasn’t concurred yet.” So I said, “Well that’s a good excuse.” You always, as an owner, say, “I’ll do this, but …” So I kept that hope out there, that he was gonna be a part of the Laker organization. [...] Andy Miller: I think that what McHale was looking for, on top of picks, was a core young piece, and he was infatuated with Al Jefferson at the time. Glen Taylor: It became the Lakers, and it became Boston. And they both said, what does [Garnett] want to get paid? And I told them what he wants to get paid. I told them the kind of contract. And those two teams said they would do it."
Luckily for Boston, the McHale infatuation with Jefferson (and quite possibly his old ties to Ainge) aligned with the moves Danny had just made with Allen, and they had an ownership group with deep pockets and the will to compete. It hasn't always been that way, and while we're still spoiled in that regard in the present, the history of the league is littered with could-have-beens whose window was closed early or before it ever really opened all the way for lack of resources from ownership. But then, as now, fortune smiled on the Celts, and with good luck, star power and a unified team, well, you know.