Tatum had a really good season last season, 27 pts / 8 rebs. As to 3P%, he was 229 for 609 last season (37.6%). If he makes only 15 more in the season, he will be over 40%. He ends up being the guy who is forced to take many of the end of shot clock shots or other more forced shots, but I think he will be more consistent from 3 this season than last.
Overall, he is our top scorer and rebounder and second best assists. I don't think people fully appreciate how important his rebounding is. He got 534 rebounds last season. Horford only got 331 and Porzingis only 312, our next two highest. I know this whole play big/play small thing has been debated to death but the only reason that we can play so often with one big and keep so many scorers on the floor is because of how well Tatum rebounds and defends opposing PFs. He had 364 total assists, 2nd only to Derrick White at 377, so he is distributing at a high level too.
This versatility, to be the top scorer and the top rebounder and defend wings at a high level and defend PFs at a high level and produce about 5 assists/gm, seems to not get fully recognized. He probably is a little salty and probably will come back strong and maybe his best season ever. But they will find something to criticize him on. If his 3P% is up a little, maybe his rebounding will be down a little, whatever, they will find something.