Mowbray also urged his players to respond in the next game and show him they are worthy of a playoff place.
"It was a poor performance from us and there are no excuses," Sky Sports News quotes Mowbray as saying.
"We came here in a positive mood thinking we could get three points, hoping to push on and put pressure on the top two again.
"Now we're looking for a reaction because today wasn't good enough. We've lost four on the bounce and we either curl up and die or come out fighting, to show our credentials for a top-six place.
Boro currently hold sixth place in the Championship.