For people that don't watch Boston all the time, they give up a lot of three-point attempts and most of the time encourage them. That's how they play. They often get long rebounds, are then off to the races, and either get easy points at the rim or kick outs for wide open threes. Many times, that's how they go on 20-3 runs.
What I didn't like last night is how the Heat defended them. Miami started to double guys way past the 3P line, and rather than defend a player, they defended passing lanes. That led to multiple bad passes / steals / turnovers. They didn't really turn into point for Miami, but they prevented Boston from catching up. In the second half, the Celtics got a lot of shots close to the rim and missed and didn't get rebounds.
I agree with Mazzulla's post-game comments that you are in trouble when a team is shooting 55% from three and you are shooting 45% overall with a lot more two-point attempts. Simple math confirms that. Joe said the answer was to play better and more efficiently on offense. My concern was they usually get a lot of open looks on threes by driving and kicking. Miami gave up easy two-point shots and took away the kicks for three pointers. That essentially took Holiday, Horford, Hauser, and Prichard out of the game.
As for Porzingas, he had a defensive rating of 108. The other Boston starters were in the 120s (and that was better than 4 of the 5 Heat starters). He didn't do much offensively and had one of his worst game scores on the season. Same thing with Holiday. Those two had two of their worst games on the season and Prichard didn't score in 20 minutes of playing time. That's almost 90 minutes of game time between them at extreme negative productivity.
A win is a win for MIA (or a loss is a loss for BOS), and the simple assessment is the Heat are unlikely to make that many threes again and multiple Boston players are unlikely to do close to nothing again. The Celtics need to have more intensity, be more committed defensively, and not be as sloppy. They didn't have a ton of turnovers, but they all game at bad times.