The spotlight is too bright for the Mavs -they are a young and inexperienced team and for most of their players it’s their first ever nba final experience . Kyrie is the only player in the mavericks roster with nba finals/championship experience. He’s also the only veteran and the oldest player on this team.
Kidd had three nba finals under his belt as a player but it’s his first ever nba finals as a head coach.
The far more experienced Celtics core (Al horford, Jaylen brown, Derrick white, jayson Tatum ) went to the finals two seasons ago. And they added the veteran jrue holiday who won a NBA championship with the bucks 3 years ago. They know how to act on the league’s biggest stage because they have been there before.