Which of the 2 Possible CP changes are there?
I can think of 2 possible explanations.
1) Pokemon's base attack, base defense, base stamina didn't change. All they did is change the formula to not make Attack count twice as much in the Stamina & Defense.
If this hypothesis is true, not changed on relative usefulness of pokemon, just thier CP for sitting in a Gym.
2) They changed how they calculated base attack or base defense.
If this is true. Then all the Ranking Type Pages will need redoing with the new attack/defense values.
Which do you think happened?
Answers
Given that some pokemon like Poliwrath and Wigglytuff have gone down and others like Pinsir and Machamp have gone up, it is not just a change to CP formula. There has to have been a change in the base stats. Of course it still could have been both changes, but at the very least base stats have changed.