I think you have to break Dak's season into two parts, the first 7 and the last 9 he played.
Also, how many TDs he threw is not as relevant as when he threw them. Some Dak critics accuse him of padding his stats late in the game. I would argue that was certainly possible against the Cardinals and 49ers, Denver too. But the Bucs game was close and they did come back to tie the Raiders late, even though the offense was ineffective early allowing the Raiders to get to a big lead.
At the end of the day, It is hard to argue that late in the season Dak played well. Many very knowledgeable football analysts claimed Dak was slumping, or not playing as well as he could. The rest of us could just see it with our own eyes. Dak was awful against the Cardinals. And he was not very good against the 49ers either. I know his defenders will say it was the offensive line. But there were plays when he had time to throw and he did not make the big plays. He gets paid $40 million. When the opportunities present themselves, he should be taking advantage.
At this point, I think the discussion should be more on what to do now knowing Dak is with us for at least another 3 years. The consensus seems to be fix the OL and run the football. I agree. The threat of the run will make Dallas a much better offense even if they score fewer points.