Lee has been a PF his whole career. That's the position he defends best.
PF's don't have to be shooters.
Here's where you are wrong, ....
There's no required or strict skill sets for each different position, it's about where they fit offensively and defensively and who they defend. There's point guards in the NBA who are essentially spot up shooters on O but they defend PGs ( Delly w/ Cavs, Fisher w/ Lakers, Chalmers w/ Heat, Mills with Spurs), there's centers in the league who can shoot from 3 or long two's in pick and Pops (Hawes, Marc Gasol, Horford, Cousins). There's SF's or SG's in the league that facilitate the offense for their teams and play like how a "PG" should play. (LeBron, Kobe, Harden, Kawhi, Durant... to name a few).
If teams stay traditional and don't go small, then Dedmon, Lee, Bertans, Manu and Mills makes a lot of sense. IMO
Anderson is closer to a PF than Bertans. Bertans is quicker, more athletic (not saying much) and can space the floor better with his elite shooting.