Kon had the ball in his hands a ton especially by the end of the season. Feel like he was bringing the ball up more than Flagg towards the end. I don't really think Scheyer made a mistake, they were legitimately the best team in the country by a ton. They just had an all time choke in the last 5 minutes.I don't think Kon was a guard at all, I think he was a SF. Duke had ridiculous talent at SF, PF and C. Sion James and Tyrese Proctor were an imbalanced backcourt. Scheyer tried to go positionless with Flagg as a point forward - bad idea.
There is a difference in play/style at the college level and NBA. In CBB they're kids, haven't faced major pressure and usually only play together for 1-2 years these days. NBA are men, play together for years. Why the PG is a factor in college.
On the other note, I think PG is a huge factor in the NBA too. I don't think it's a surprise that you've seen the Thunder, Pacers, and Knicks have a ton of recent success.
The spurs shared duties a bit more than the rest and Wemby is obviously a freak but I think the lack of point guards in the NBA also benefits them. You see a lot of teams that play San Antonio trot out "point guards" that legitimately can not dribble the ball up the court against Castle and it derails their offense(similarly the Thompson twins create this issue for a lot of teams).
Going position less might be great for the regular season but the last two playoffs have been dominated by SGA, Brunson, and Haliburton.