From our friends at ESPN Stats and Info: When the Boston Celtics take the court on Saturday, they'll try to become only the fourth team since the ABA-NBA merger in 1976-77 to make the conference finals after entering the All-Star break under .500. Boston stumbled into the break at 15-17 this season before surging to the Atlantic Division title and, now, the cusp of the Eastern Conference finals. The last team to accomplish the feat was Phoenix in 1983-84 (the Suns lost to the Lakers 4-2 in the conference finals).
A glimpse at the three other teams to accomplish the feat:
1983-84 Phoenix Suns -- Lost in conference finals
1980-81 Houston Rockets -- Lost in NBA Finals
1980-81 - Sacramento Kings -- Lost in conference finals