Last season, it was no secret that the Celtics under-performed. They were the seventh seed and lost in the first round to the Brooklyn Nets. Throughout the season, they suffered many set-backs. Kemba couldn’t play back-to-back games due to his injury, Brown missed the whole playoffs with an ankle injury, and they had the most time missed by players in health and safety protocols, including Jayson Tatum. Injuries are unpredictable but hopefully this year we will be luckier. 
Even without injuries there are plenty of questions that the Celtics must answer if they want to have a successful season:
What does success look like for this team?
Success does not necessarily mean always winning the championship. Let’s look at the Knicks for example. Last season was a successful one for them because they did much better than many people expected. For the Knicks to be comfortable in the playoffs after nearly a decade as a bottom feeder team was a success. They were able to develop Julius Randle into an All-NBA player, they were able to see lots of potential in Immanuel Quickley, and in the off-season they acquired players who could help them win even more games.
The Celtics have to evaluate what it means to be successful this season. Do they want to win a championship right now, or do they want to continue to develop young players? This off-season did not make their decision clear. They traded Kemba, who despite having a history of injury, could still have helped them win games, and they let go of Moses Brown who had a lot of potential. They also signed a mix of younger players, who might still have some potential, and older players who can help them win now.
Personally, I would love to see a big jump from Payton Pritchard and Robert Williams. I hope that Pritchard can improve his playmaking and develop his skill as a starting caliber point guard. I would also like Robert Williams to continue the skill he showed in his breakout season last year, and to continue to improve his defensive intensity. Aaron Nesmith is another player I want to see advance his skill. Hopefully, if given the chance, he will have to ability to become a reliable three and D player.
Can Jayson Tatum and Jaylen Brown be the two best players?
For the last couple seasons, the Celtics have surrounded Tatum and Brown with other All-Star caliber players. Since they’ve been together, they have always had either Kyrie, Kemba or Hayward on the team. This will be the first season that Tatum and Brown will be the clear, and uncontested, first and second options. Obviously, last year you could argue Tatum and Brown were already the first and second picks, but trading Kemba Walker really solidifies this fact.
Last year, Brown proved that he deserved his max-contract by becoming an All-Star for the first time in his career. However, is this enough? The All-Star duo last year played really well yet the team did not perform well. Again, it wasn’t completely their fault, there were a lot of injuries the point still stands, can they be your two best players on a championship team.
How good of a coach is Ime Udoka?
One of the biggest changes from this off-season was our coaching change. This summer, Celtics Coach Brad Stevens was promoted to Celtics General Manager after Danny Ainge retired. After weeks of looking at potential coaching hires, it was decided that Ime Udoka would be the future coach for all upcoming seasons. 
Udoka has never been a head coach, but he has been on the staff for many great teams over the years, like the Spurs, 76ers and the Nets. Most notably, he was a member of the coaching staff of the 2019 FIBA World Cup team, where he coached three current Celtics players. One of the biggest criticisms of Brad Stevens’ coaching style was that he was unable to motivate his players. However, Udoka— who was endorsed by players Tatum, Brown and Smart—already has a great reputation with the players on the team, which will hopefully translate to motivation in the locker room. Will this be enough, though? We will have to wait and see.