It is when teams effectively can say, "Uh, never mind."
It is the first day that players signed in the offseason can be dealt.
While the Feb. 18 trading deadline remains the league's ultimate personnel benchmark, Dec. 15 essentially is the starting gate for in-season maneuvering, when the bulk of the league stands trade eligible.
That also makes it the perfect time to evaluate the signings from this past summer, as teams debate whether hold 'em or fold 'em.
Ron Artest, Lakers: There have been no signs that this won't work. OK, at least no on-court signs. Now Kobe Bryant doesn't have to do all the heavy defensive lifting on the perimeter.
Shannon Brown, Lakers: If for nothing else than the slam-dunk relief to a humdrum season of constant victory.
Trevor Ariza, Rockets: Houston needed less drama and more consistency than Artest provided. The swap-out of small forwards appears to be a win-win situation.
Channing Frye, Suns: The difference between Frye being marginalized in Portland and thriving in Phoenix is Alvin Gentry accepting him for what he is, an outside-shooting big man. What seemed like a minor signing has turned into a major addition.
Rasheed Wallace, Celtics: Make no mistake, there will be more than a few moments along the way when Wallace drives Doc Rivers to distraction. But this was never about the regular season. Come the playoffs, Boston will be much better suited to deal with an injury or off night by Kevin Garnett, or the ever-present foul trouble of Kendrick Perkins.
Jason Williams, Magic: This under-the-radar addition might wind up providing more bang for the buck than any minimum-scale signing this offseason, in light of Williams' performance in the injury absence of Jameer Nelson.
Joe Smith, Hawks: The type of move that will pay its ultimate dividends in the postseason. A perfect match for a roster in need of veteran savvy.
Mike Bibby, Hawks: While giving Bibby three more years might have seemed like a reach, Atlanta deserves credit for appreciating that its future is now.
Anthony Parker, Cavaliers: Cleveland certainly did not know at the time how the offseason was going to play out with Delonte West. As it turns out, Parker has turned into a reliable insurance policy.
Flip Murray, Bobcats: He was productive before being injured. Now, with a perimeter rotation bolstered by the addition of Stephen Jackson, he could turn into a prime Dec. 15 trade chip, with Larry Brown in search of an active veteran big man.
Dahntay Jones, Pacers: The hope was Jones would be a supporting player. But the failure of Brandon Rush to consistently produce has allowed Jones to have his moments not only as a defensive stopper, but also has a scorer.
Jason Kidd, Mavericks: He remains the motor of a consistently efficient engine. The three-season term of the contract should ensure continued productivity.
Antonio McDyess, Spurs: Nothing wrong with cheap, efficient labor, considering only the first two years are fully guaranteed.
Matt Barnes, Magic: A subtle move to enhance depth that allowed the Magic to survive Rashard Lewis' 10-game suspension at the start of the season.
Drew Gooden, Mavericks: While the starting role was a bit much, Gooden has provided a quality mix of height and skill, certainly a value at $4.5 million for one season.
Juwan Howard, Trail Blazers: A minimal move that proved prescient planning for a team that has lost Greg Oden from its power rotation.
PBT: Have the Grizzlies figured out San Antonio, or will tonight's Game 3 yield another win for the Spurs?
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