Ok, first of all, the Shooting Guard takes more shots in a match and therefore usually scores more.
Please, check the stats from the four games and look at the ratio of scored shots and shots taken at FG and 3FG.
The one with the highest ratio is the best shooter.
You are doing the right thing to play the first player as PG since he has the upper hand in passing.
I also want to add that the second player has Strong Jump Range meanwhile your PG is only at inept. Which is a great deal for a shooter.
Does this bring any light to the subject?
If not, try playing for PG as SG for four games and see if there is any difference!
-PP