The Boston Celtics have a lot of young talent that has yet to prove their true worth in the NBA. The Celtics are in a position where they are waiting for a player to break out and take over as a leader of the starting unit.
The closet the Celtics got to a breakout player last year was Isaiah Thomas as he took the city by storm. The problem is that Thomas did not break out in the sense that he did what the Celtics expected. The Celtics optimized Thomas to the fullest and he gave the Celtics exactly what they wanted when they traded for him.