After taking a 109-96 lead with 6:10 remaining, Boston was outscored 23-8 to close the game. How do you dominate a game and then just take your foot completely off the gas? The Celtics just coasted the final 6 minutes. After they built a 13-point lead, they stopped defending and started settling for jumpers. When you pair that with costly turnovers and mental mistakes, that's how you blow a huge lead.
I've got to say something about Jayson Tatum as well. I love JT and believe that he's a top 5 player in the league, but last night was inexcusable.