I suggest that you add sorting tab like it is right now for different seasons where you can choose to see only league games. Also choosing only private league games would be nice but that's not so important imho. Choosing to view only league games stats would be very useful, at least it would for me, to get a better overview of player performances in "Real Games".
currently the averages are just league games, and when you go for teamstats you could get the average stats from league game ;) That won't will make your change useless, but maybe it helps a bit till they change it when they do it.