It might be due to the weather and seasonal buffing, I'm not sure if you took those into account. The indicator on the left shows what card types get extra power. I believe in later version, it displays on the card as well so it's easier to read and understand.
While I've gotten the hang of things for the most part, I will say that the game doesn't really explain card buffs very well, and unless I completely overlooked it the game doesn't even explain card buffs to you on its own, you have to manually look it up in the help info.
