I ultimately don't think Kyrie is the player we need to win a championship, but the fans need to accept that the team has had a number of smaller failures that have just added up to a bigger disappointment. I think we could have done a few things strategically to be better, and Kyrie could have been willing to adapt to the team's makeup quite a bit better, but we were in trouble this year, regardless.
Hayward just hasn't been anything other than a non-starting rotation level player.
Horford hasn't had a great year and can't be relied on every game.
Likewise, Baynes has missed a lot of games with injuries and can't maintain his role.
Tatum isn't what we thought he was.
Morris surged early, but has regressed to being the borderline starter he's always been
Brown slumped early, and the team has struggled to establish a consistent role for him.
Rozier was handed a diminished role and has handled it badly.
The net result is there is no one established in a reliable scoring role for this team except Kyrie. The expectation was that Tatum would be that guy, and that Hayward would be getting there by now. Both guys have been big disappointments.
For their part, Ainge and Stevens could have had better years too. Ainge should have cared about roles more, and moved Morris and Rozier.
Stevens should demand that the team to play faster and move the ball more consistently. I also just don't understand what he is doing with Jaylen Brown. He's the only one on the roster right now who looks like he should be doing more. Try him as the second option and see what happens.