On January 20, the Boston Celtics hit their low point. They lost at home to a bad Phoenix team and fell to 5-9 on the season. General manager Danny Ainge was talking openly about trading any of the team’s Big Three—Kevin Garnett, Paul Pierce and Ray Allen—who’d won one championship together in 2008 and been to the Finals together in 2010. It seemed as though the only question left was whether the Celtics could even make the playoffs, as they were in a four-team joust with Cleveland, Milwaukee and New York for the final two spots in the eight-team Eastern Conference bracket. Then things changed. Since January 20, Boston has won nine of their last ten. The SportsNotebook takes a look at how they’ve done it and what the odds are of sustainability.