One thing to note is that on his player page's career stats window it shows 17786 points. In team history page it is over 20k yes, but that is only accessible to supporter teams. I don't know where the extra stats come from there, maybe bbm matches?Regardless, I checked some historic NT team players from my country and no one has more than your guy. I feel like to beat your record it has to be a player from lower division, who has been stat padding a bunch of +30 ppg seasons ;)
It is better to check on Buzzermanager. Of course the pickup games will not count. All you have to do is to update all schedules of your team and after that go back to My team-Records and select Players career and all types of games.