This Duke team is the 3rd best in Duke Kenpom history in 3pt%, only slightly behind 2014. 2013 is way out in front, mainly carried by Seth Curry's high volume 44%.
I'd say "shoot more 3s" but this Duke team also happens to be 2nd best in Duke Kenpom history in 2pt%, only behind 2002, which featured 5 starters so good at making 2s that Jay Williams was the worst among them.
Combine great 3pt and 2pt accuracy with the #1 offensive rebounding in Duke Kenpom history, and of course, this is by far the best offense in Duke Kenpom history by adjusted efficiency.
Looking at it from this perspective, it does seem silly to worry about the whole dynamic surrounding Duval/Bagley/Allen offensively, since the offense is close to hitting a realistic ceiling as is. The only realistic room for improvement seems to be in FTs (both getting to the line more and being better at making them) and turnovers. These factors are heavily decisionmaking/scheme-dependent (as opposed to talent-dependent), which means they should be improved fairly easily, which in turn means it's not a waste of time to try to improve them.
The turnover rate actually isn't that bad relative to all Duke teams. 17.0% is Duke's worst turnover rate since 2012, but on an absolute scale, it's not terrible. 2015, with great passers and high IQ in the backcourt, was not much better, at 16.3%. With how great Duke's offense is overall, each turnover basically subtracts >1 point against even the best defense, and the cost of each turnover is magnified. Less Duval running the offense and more Allen running the offense should cut this down naturally. Allen's ACC-only turnover rate is 16.9% this season. Duval's is 25.9%.
The FT% and FT rate are a little more difficult to improve, but still very much doable. This team has the worst FT% in Duke Kenpom history and by far the lowest FT rate. This may seem like it's fine, since maybe a poor FT shooting team should try to get to the line less, but no, the answer to bad FT shooting is not to take fewer FTs. This is the biggest area for Duke's offense to improve.
At 69.6% from the line, Duke as a team would be expected to score 1.4 points per possession in the double bonus and for any shooting foul, against any defense in the country, which is much better than what the offense would do on an average non-FT possession against a decent defense. They need to get to the line more, and they should be doing it with their best FT shooters. Which player is best suited to provide this boost? Of course it's Allen. And of course Bagley and Duval are the biggest drains on Duke from the line.
More Allen in general, more Allen drives in particular, less Duval in general, less Bagley iso/post-up clogging the paint, more Bagley rim-running to hunt rebounds and putbacks when Allen gets into the paint. This helps everyone involved - it exposes Duval's weaknesses less for NBA scouts, it makes Bagley more appealing as a modern day NBA 4/5, it potentially puts Allen back on the NBA radar, it helps the coaches win more games.
Carter and Trent should probably just keep doing what they're doing. Maybe run more plays to get Trent open from 3.
The good news is, the coaches seem to be coming around to all of this. The bad news is, it has been happening most recently with Bagley completely off the court due to injury (or "injury"), so we can't be sure it will continue once Bagley is back.