Tatum averaged 14.6 points and 5.9 rebounds over the month, while shooting just under 53 percent from the field and just over 45 percent from 3-point range.

The 19-year-old's strong play also helped pace the C's to an 11-win December and finish the calendar year with a league-high 30 wins.

It was the team's first such award, since Marcus Smart was named Eastern Conference Rookie of the Month in February of 2015.