with regards to ur question, you will also notice that the opposition SG has average GS and probably poor defense, so from that perspective, his PP100s would be high. I also guess one of the reasons why pp100 was so high for my player was because the mismatch of defensive attributes (OD,ID, Blk vs JS, DR, IS). Usually SG could be weak at ID and Blk, so my player who has high IS could have such high pp100.
with regards to ur question, you will also notice that the opposition SG has average GS and probably poor defense, so from that perspective, his PP100s would be high.