Jaylen Brown has been around for plenty of big games by Tatum, but he knew this one carried a little bit more weight. “It was a big-time performance,” Brown said. “Our backs are against the wall, too. You love to see JT come out aggressive and carry us offensively like he did forcing Game 7. Definitely a signature game for the Celtics and for Jayson.” Tatum, Brown and Smart combined for 89 of Boston’s 108 points as Brown went for 22 and Smart had 21. The trio combining for 82.4% of the Celtics’ points marked the second-highest percentage by a Boston trio in postseason history behind only Dave Cowens, John Havlicek and Jo Jo White scoring 80 of 91 points on April 20, 1973, according to ESPN Stats & Information research.