If you want the #'s to work properly for PNRs (I.E. '13' being the actual 3, '14' the 4 and '15' the 5), you should take the "Pick & Roll Man" play off of EVERYONE on your team. If someone on the court has that play type (usually bigs), they're gonna be the roll man every time no matter what you call. If you remove that play type from everyone, then the play calls will operate properly, and 13's will be set by the SF, 14's the PF and 15's the C.
I just went in and verified (I did it with the Bucks) that even if you assign the play type to Durant (and say, Ibaka or Adams has it also), you won't get him as the roll man every time. I had Giannis/Parker/Monroe all with PNR Man, and called Fist 13, and whoever is the closest to the ballhandler will come up for the screen. I got Giannis to come over when he was right next to me, and Monroe came up the other 2 times.
tl;dr = remove "Pick & Roll Man" play type from everyone on your team.