First of all I really like the top 6 of our current roster in the order of Tatum, Walker, Hayward, Brown, Smart and Theis. Also Kanter is a worthy rotation player. But after that the roster is incredibly weak. Of all the playoff teams the Celtics may have the least depth of all of them. This in contrast to last year, when players were fighting for minutes.
Below I have the roster of last year and we all know now how Irving became a big locker room problem and that this was a big reason for them to underperform. Nonetheless if you look at that team I think you have to agree that it should have been a championship contender.
Lots of changes happened in the summer of 2019, but the downgrade in talent is clear as day. Naturally Tatum and Brown made a big step in their development and also Hayward and Theis are better than last year, but that doesn't make up the amount of talent we lost. Even if the top 6 are equally good, the bench will kill us. Therefore I don't understand why there are Celtics fans (and also general NBA-fans) who believe that we have a reasonable chance at a title.
Roster 2018/2019 season
guards: Irving, Smart, Rozier, Wanamaker
wings: Tatum, Brown, Hayward, Morris, Ojeleye
bigs: Horford, Baynes, Theis, R.Williams, Yabusele
Roster 2019/2020 season
guards: Walker, Smart, Wanamaker, Langford, Edwards
wings: Tatum, Brown, Hayward, Ojeleye, Green
bigs: Theis, Kanter, G.Williams, R.Williams, Poirier
Irving => Walker
Rozier => Langford
Morris => Green
Horford => G.Williams
Baynes => Kanter
(Yabusele => Poirier)