The Midlands club were battered away from home on Boxing Day, denting their Champions League qualification hopes.
A red card to in form striker Jhon Duran for violent conduct only made matters worse.
Emery stated post-game: “We started the first 30 minutes conceding one goal. We made a mistake conceding it.
“And, of course, here, to start losing is difficult, but we reacted very well.
“The first 30 minutes, we were more or less feeling comfortable and feeling confidence to continue in our game plan and try to get something.
“After the red card, it was more difficult, of course. Maybe it’s unfair, the decision. Maybe it is a red card, maybe not, but we have VAR to try to take time with the decision.
“The only person who can take time is the referee, and he decided red card.”