You have gotten excellent answers and as said it is a guide only. I have a SF on my team, Marko Sperbert, who I can play as PG, SG, SF or PF. My PF Lawrance I have played as a C, PF, SF and even SG. My SG Vallo Tammela was for a long time playing every game at PG. My C Garth Larbi mostly plays PF but does some C and even was a SG once this season. My SG Kumar has played more PG than SG and done a lot of SF. While doing all this I have only lost one game for the season. So as you can see the positions are a guide (as said they are technically at which position their salary is highest) and nothing more. You can play anyone anywhere if it is the correct call for the tactics and matchups.