I do think Porzingis should be offensive option #2 on that team late in games.
Brown is just not that creative of an offensive player. He is great over an entire game, but at the end of the game I would go Tatum or Porzingis if you are going to call a play for a guy. Then you have so may other good offensive assets (Brown, Jhrue, Hauser) if the other team goes too aggressive on Tatum/Porzingis.
Haven't watched a ton of Celtics this year, but Porzingis has always been a great single possession guy.
These strength of schedule need to be taken with a grain of salt.
We played Kings twice with no Fox and will play Nuggets twice with no Murray.
Do they take that level of stuff into effect? Because injured key players really lower the level of a team.