Kevin Garnett arrived in Boston five years ago with the promise of rebirth for a franchise that had grown stale. He was a savior then — plucked from Minnesota for almost half a roster’s worth of young players and draft picks ‘ and he was treated as such.
On a team of prideful individuals, Garnett’s persona stood out as the defining one. Dedicated to the point of insanity and private to the point of aloofness, Garnett kept close watch over his basketball family and kept everyone else at bay. Something changed over the course of those five years, culminating last season in a Garnett that was slightly more accessible and endearingly human.
No one could have predicted five years ago that Garnett would ultimately become an institution, but here we are. He’s become one of us: a Bostonian in more than just an address and a Celtic in more than just a uniform. When his contract expired, there was never a question of going anywhere else, it was only a matter of whether he’d come back for more.
We have our answer, as Garnett will sign a new deal, reportedly for three years and $34 million , roughly half the monetary value of his last contract, and assuring he will be in a Celtics  uniform for almost a decade.
Garnett’s new deal sets in motion an offseason that now takes on a defined shape. The Celtics are still contenders, and team president Danny Ainge has flexibility to build the rest of the roster. Salary cap economics being what they are, Ainge is limited to a degree, but he has a host of options at his disposal that weren’t as obvious 24 hours ago.
Including Garnett and their two first-round draft picks, the Celtics have about $45 million in real money committed to the roster for seven players. They still have significant cap holds on players like Ray Allen , Brandon Bass  and Jeff Green  — totaling more than $34 million between them — so their books are not yet clean to pursue free agents from other teams.
Ainge could create real cap space by renouncing the rest of his free agents, but that would leave him with a little more than $10 million, and the free agent class is one of the weakest in years. It’s far more likely that he will try to re-sign several of his own, beginning with Green. That would likely take him over the cap, estimated to be at $58 million for the upcoming season.
Depending on how new deals for those players shake out, Ainge could maneuver the Celtics under the luxury tax line for the first time since the 2008 season. That’s significant because under the terms of the new collective bargaining agreement, teams that are under the tax — roughly $70 million — have access to a larger mid-level exception and a bi-annual exception.
Among the priorities are finding scoring on the wing for the second unit and more bulk and rebounding inside. Those players don’t come cheap, but there are options even in this limited class, such as O.J. Mayo and Jamal Crawford . Having access to the full mid-level — a four-year deal starting at $5 million per — gets you in the ballpark.
Garnett’s return is the most important development of the C’s offseason. He is their anchor defensively and remains an outstanding inside-out threat on offense. With two promising big men added in the draft, his presence and veteran tutelage are more important than ever.
The 2012-13 Celtics are far from a finished product, but the Garnett era also is far from over.