How does Djokovic handle Berdych so easily whereas Andy always ends up in a really tough battle?
Especially when you consider how similar their game styles are.
Most of Andy's matches against Berdych have been on clay. Thr second reason, in my opinion, is that Andy likes to play more on the backfoot against the oponents outside of the top 4 and that is a good thing from Berdych's point where he can stay in the middle and rock his forehands. when Andy made him run in their last match, Berdych had no chance.
Djokovic, on the other side plays quite aggressive in the last 2 years, as has Andy started in recent history.