"Bulls---. That's bulls---," Smart said when asked Thursday if Irving's leadership skills were behind the Celtics' lack of chemistry. "Not one of us on this team knows what Kyrie has been through. Probably a few amount of people in this world know what Kyrie goes through. It was hard for him as well.
"He was forced into a situation where it was business over the friendships. He had to come into a situation knowing this is a group of guys that had something going before [he came] here. 'How will I fit in?' He didn't want to disrupt that. That says a lot. This is Kyrie Irving we're talking about it, and he's worried about coming in and disrupting us. We took him in with full arms. We tried to understand. But like I said, we never really understood because we're not in his shoes. That's just a bulls--- statement to say his leadership skills killed us."
Irving went 25-for-83 (30.1 percent) from the floor in the Celtics' four losses to the Bucks -- including 6-for-21 shooting in their final game Wednesday.
"We just couldn't find a way to do it. It's nobody's fault. It happens," Smart said Thursday. "... It's four other guys out there, 13 other guys on the team. Coaches and everything. To just blame it on one guy is bulls---."
Celtics guard Jaylen Brown is was "an up and down season from all of us" and acknowledged that it was a struggle to put all the pieces together.
"I don't think anybody was prepared for this year in terms of what the circus was going to be like," Brown said. "The media and everything. The expectations and balancing. The rotations, we didn't know what it was going to be like."
Smart said he has not talked to Irving, who can become a restricted free agent this offseason, about a possible return next season.
"If he wants to talk about it, he will," Smart said. "That's his decision. Not for me to ask. Not really my business. I love Kyrie as a brother. I talk to Kyrie. I wish nothing but the best if he decides to stay. If he decides to go, I wish nothing but the best for Kyrie. It's my brother. But I have not talked to him and I do not plan to. It's his decision."