It started with a two-seed drop in the Eastern Conference, falling from first to third in the conference in the final weeks of the season. After the dismantlement of Carmelo Anthony and the new-look New York Knicks in a 4-0 sweep in the first round, the Celtics would find themselves out-matched by the explosive offense of the Miami Heat.
It was a season of disappointment, as next season might be the last season that the Big Three - Paul Pierce, Ray Allen and Kevin Garnett - will be playing together with the Boston Celtics.
Going into the off-season, Rondo and the Big Three all have different areas in which they need to spend time working on to better their games for the 2011-2012 season.
Here is the specific area that each of the five Celtics players - those which are returning for the 2011-2012 season - need to improve upon going into next season.
Avery Bradley averaged just 5.2 minutes per game in his rookie season with the Boston Celtics. He was a part of the rotation for 31 games and proved to be a solid player with much promise in the future for the C's.
The 20-year-old will likely get more minutes next season, as Rivers might try to test out Bradley more when he can afford to.
Bradley is a player that needs to improve the consistency of his jump shot, as he has proven he is a quick, athletic talent that can get to the rim and finish.
A key asset to the Celtics in the frontcourt rotation, Jermaine O'Neal, has said he will likely return for the 2011-12 season as a member of the Celtics.
O'Neal is a player known for his rebounding and shot-blocking ability, although he is also a solid scorer on the interior. Last season, O'Neal averaged 5.4 points, 3.7 rebounds and 1.3 blocks per game in just 18 minutes of play per contest.
Talk about efficiency.
The guy makes the most of his minutes. The problem is that the Celtics would be a better basketball team if they could play O'Neal anywhere from 20-25 minutes a game. It should also be noted that O'Neal is a player that plays in spurts, putting up most of his production in a short amount of time.
That is a clear sign of a player who is aging and becomes fatigued more quickly. If O'Neal expects to produce in a strong way for the Celtics next season, he needs to hit the gym and improve his stamina.
Ray Allen is a player that is known for being able to do a little bit of everything. For one, he can shoot the ball as well as any player in the history of the league.
This past season he passed Indiana Pacers great Reggie Miller, for most three-pointers hit by any player in the history of the NBA. Last season he also shot 49.1 percent from the field and 44.4 percent from three-point range, both career-high numbers for Allen.
On defense he could make some adjustments, but is ultimately a player that plays tough defense and does it to the best of his ability. His problem is more in his ability to score the ball consistently for the Celtics.
He might hit seven three-pointers one night, and then go for just one the whole next game. Allen could score 24 one game, and maybe just 11 the next. If Allen wants to improve on one area of his game, it would be his consistency scoring the basketball.
KG has proved time and time again that he is a player that likes to find his sweet spot on the offensive end.
Although being known for his defense with the Boston Celtics, Garnett is also known for his aggressive play offensively and ability to find his jump shot. With offensive talents like Paul Pierce and Ray Allen playing alongside him, at times Garnett will shy away from asking for the ball in the block.
If the Celtics expect to win a championship next season, Garnett must play a bigger role in the offensive scheme. He has proven over the course of his career that his baseline jumper and mid-range game are arguably as good as any power forward today.
If Garnett would look to score the basketball more, it could benefit the Celtics going into the 2011-12 season.
When there's a Rajon Rondo, there's a defender about 150 feet away.
Since Rondo became the starting point guard for the Boston Celtics, it has become a consistent defensive scheme by most teams to play no perimeter defense on him.
Rondo is left with anywhere from five-10 feet of space to take an open jump shot, and yet teams let it happen because Rondo simply can't make them pay on a consistent basis. As a top point guard in this league, Rondo lacks a jump shot, which separates him from players like Russell Westbrook in Oklahoma City, Chris Paul in New Orleans, and Derrick Rose with the Chicago Bulls.
In addition to his poor jump shooting, is his lack of consistent free-throw shooting. Rondo shot a career-low 56.8 percent from the free-throw line, while averaging a mark of 62.2 percent for his entire career.
These are numbers that must improve if the Celtics want to win in the postseason and if Rondo wants to prove his worth as a top point guard in this league.
Paul Pierce will go down as one of the better players to ever throw on the green and white.
It is hard to pinpoint flaws in a player like Pierce, who does a lot of everything for this Boston Celtics team.
He plays hard defense, has a solid mid-range and three-point shot, and can pass and rebound the ball fairly consistently. Pierce is also known as being one of the better free-throw shooters in the league, shooting 86 percent on the season.
The problem with Pierce is that he is an emotional player, which can help a team, but ultimately becomes a problem when it gets out of hand. The more recent example came against the Miami Heat, when Pierce lost his cool with both James Jones and Dwyane Wade in just under one minute of play in the fourth quarter, finding himself ejected.
It was a win the Celtics needed, and they had to do it without their star player in the final minutes of the contest. If Pierce wants to improve on one area of his game, he should keep his emotion for the positive moments and lead by example. Getting technical fouls because of frustration towards a significantly lesser player like Jones is simply unacceptable from a player of his caliber, especially in a must-win postseason game.