As someone who only pays close attention to the Celtics, I am surprised that people expect them to make it to the finals. I am guessing they will get knocked out in the second round or conference finals. They have a lot of wins, but it is because they take care of business against lesser teams. When facing another top team, they fall short. They are 0-2 vs the Spurs, 0-2 vs the Nuggets, 1-2 vs the Knicks, and 1-3 vs the Pistons, though they are 1-1 against the Thunder.
They should be able to dominate a play-in team in the first round but after that, they are going to face strong competition and they have not shown the ability to rise to the occasion.
Obviously, most of those games were without Tatum, but he is not fully back either. His scoring is great but his accuracy is abysmal. He is missing badly on shots he expects to be automatic, likely because coming back from his injury took a toll on his body and he is still getting used to his limits.