Okay here I got a screenshot with this problem in action. I have my mouse cursor over the pet dragon experience bar. Notice it says experience gained 9404 which is exactly correct according to what the game told me in battle. I was getting 154 experience per mana ball and I put down somewhere around 60 plus I got some more experience from putting up walls and such.
BUT look how much my pet dragon actually gained, only about 300. Now WHY!?!? This is even less then last time when I gained about 700. What the HELL is going on here?
Maybe I should mention how I did this exactly. I had about 4000 out of control peasants which I let destroy the enemy troops then I ran around and avoided the peasants until I ran out of goblins to sacrifice, then I killed the peasants down to about 500 at which point they came back under my control and the battle ended. I don't know if this could have anything to do with my problem. I tend to doubt it because the game did say I gained the correct amount of experience.