Second Post lists all of these changes.
io is referring to this list which Nintendo provided prior to July 1 (and which the new values for old games list seems to mirror). He and probably others made a decision on when to register games based on that list. So when the time for the values actually came around, some values that were supposed to hold, fell. I noticed that the vanilla :wii:Animal Crossing was supposed to hold at 50 went down to 20 as well as :ds:Pokemon Conquest, which went from 40 to 30. No one noticed more of the discrepancies in the list of new values for old games until now.