I only see 2 options:

1: TH3 is actually just TH2+1
2: They globally decreased drop rates to balance things with TH3 since TH3 was really only added to keep THF relevant and not to increase the amount of treasure we get.

I'm leaning towards option 1 because option 2 would require a lot of man hours. We need a new TH2 test to compare too >.<