Sullinger was impressive in the team's preseason debut on Friday against Turkish team Fenerbahce Ulker and scored 16 points and grabbed eight rebounds
The Celtics were not able to beat the Miami Heat in the Eastern Conference Finals last season because they didn't have enough frontcourt depth due to injuries to Jeff Green and Chris Wilcox.
Whenever Kevin Garnett needed a break and took a seat on the bench, the Celtics' opponents in the playoffs would make a run and get back into the game because Rivers had no one to give the team any where close to the impact that Garnett made.
Sullinger is going to give the Celtics more depth at the power forward position and a much-needed back-to-the-basket post up scorer in the paint.
Playing on a strong defensive team like the Celtics and alongside great defenders such as Garnett will help Sullinger's defense quite a bit. He's not a terrible low-post defender, but it's one part of his game that needs a bit of work.
The Celtics didn't have too much firepower off the bench last season, especially in the frontcourt. Brandon Bass provided some scoring from the power forward spot, but he was forced to make 59 starts last year because of injuries to other forwards.
The former Ohio State star will give the Celtics scoring off the bench when Garnett needs a rest, and he will also give the Celtics another option in transition. He was one of the Buckeyes' primary scorers last season and played well in high-pressure situations against top teams.
Sullinger is going to play a key role on the Celtics front line this season, and if he can have a strong rookie year, Rivers will have the depth and scoring that he didn't have during last season's playoff run.
Boston will be one of the top championship contenders in the NBA this season, but to win the franchise's 18th title, the Celtics need players like Sullinger to play well consistently.