Carlos Corberán was left disappointed by Albion's defeat to Bristol City in the fourth round of the Emirates FA Cup.
A brace from Sam Bell either side of Alex Scott's effort secured a comfortable fourth-round triumph for the Robins at Ashton Gate.
The Baggies were unable to produce a performance similar to the levels over that of the previous couple of months and Corberán believes there will be plenty of lessons to learn from the defeat.
He said: "It's true that the result is a big result, but we didn't show the character that we should show to kick on in the competition and that was the target."
"We made too many technical mistakes which didn't allow us to break the press or keep the ball in the middle of the pitch and to suffer more counter attacks than usual.
"We didn't attack well, we allowed them to do what they wanted to do. This is a game to reflect and to apologise to our fans because we didn't give the performance we wanted to give."
"We need to learn from this. The previous defeat in the league affected the confidence of the team.
"When you want to do tactical things well, sometimes you forget to do the basics. Compete, win second balls, make recovery runs and play with one level of mentality different to the one we had today.
"First of all today we need to feel the disappointment and apologise to our fans. Tomorrow we need to move in a different direction.
"Sometimes the pain of the defeat helps you to have an increased desire to get the win next time."
