The Potters were beaten for the fourth time this season following a Europa League match but the manner in which this one came around at Reebok Stadium was simply not good enough according to the Bosnia and Herzegovinian international.
"I am gutted. It wasn't anywhere near good enough from us. Even after the first couple of goals I felt we were still in the game, but at three and four it was impossible for us to come back," he said.
"We just kept making error after error, myself included. You get punished for that - and we did big-time.
"We have to go back to the basics that gave us the success in the first place.
"The fans are fantastic and they support us no matter what. It is apologies to them as that wasn't good enough. Hopefully we can put it right for them in the next game."