Can you point us to the game in question?
I personally think you are oversimplifying the Pitiful(High) Perimeter Defense from the post-game scouting report.
What style of offense?
What defense did you face?
It could be that the player in question took a lot of contested shots if he's the best shooter on the team and while the team defense of your opponent was rated as Pitiful(High) in Perimeter Defense, maybe they focused solely on stopping that one player leaving the rest of your players to take more open shots.
That scouting report is just a blanket statement. There is no visual evidence of how well they played unless you actually go back and watch the game to verify what you are seeing.
If said player in question is taking a lot of uncontested shots, he could have just had a really bad night. My star player has those nights more than I'd like but I prefer to think he's suffering from the "Ben Gordon-syndrome".