I like Frank a lot, but I agree, I don't see him as a starting PG in year 1. He can certainly own the spot in spurts, but if he is playing PG a majority of the time, Duke will have some issues, particularly with pressing teams.
The press isn't about how well you can dribble, it's about the passing and teamwork. Floor spacing and size are far more consistent than a quick point guard who can stay low to the ground and dribble faster than the other guy can run.
K has had a nice system against presses the past few years. Amile or a big man who can pass in the middle, guards on your wings and a safety near the basket to keep the back side of the zone press honest.
I honestly haven't seen Duke look completely inept against a zone press since the Rivers team. Hell the team the following season, the season right after the Rivers squad, made Clemson and Louisville (twice) abandon their presses and they were two of the top teams at it.
Whoever plays the PG will be fine. If Derryck comes back, he'll have to work super hard to earn it but I think he can get it. He needs to decide soon though, because Frank comes early next month and they will be on the same learning curve with the new offense.
Roll the ball out and see who wins.