It's impossible to find games. Especially a search by opening is missing.
Soon we won't even be able to find you!
I agree though. Advanced search through my played games does not allow selection an opening. I'd like to see how I perform against a specific opening, let's say 5 moves into the opening, but there is no functionality to pull up games I've played with from that starting position. Or even selecting all games with a specific ECO code. Is that something that could be implemented?