The Lencioni pyramid stacks the five dysfunctions of a team from the base up: absence of trust, fear of conflict, lack of commitment, avoidance of accountability and inattention to results. He calls it a triangle or a pyramid, whichever you prefer, and teaches it from the bottom up.
Each layer makes the next one possible. Trust enables conflict. Without it, he says, you are only trying to win the argument or manipulate the other person. Conflict is what allows commitment. You argue, and at the end you either convince someone or the leader breaks the tie, and people buy into that. As he says in the 2013 talk, people who don't weigh in don't buy in.
Lencioni calls accountability the hardest dysfunction, and it depends on commitment. You won't tell a peer they fell short on something they never agreed to. On his team assessment it is the lowest score by far, lower even than conflict. The top layer is people watching their own results over the team's: their department, career, reputation, status or bonus.
He closes the 2013 talk by running the chain backward, from results to accountability to commitment to passionate disagreement, and down to a team that trusts each other and is vulnerable.