It doesn't matter what the player is listed as thats just a suggested position. Different skills are obviously better for different positions in your case your SF will likely have lower passing and handling skills then a normal PG. Depends what the rest of your team is like and whether u can still win having a weaker player playing PG. You could pick and choose when u do 1 position training at PG. For example this week u play the bottom team, play one of your SF at PG for the full game, then play the other 1 at PG full a full game in your scrimmage. If your playing 2 better teams in a particular week u might be better doing another type of training.