The Bulls came back from their trip to Lancashire on the wrong end of a 36-24 scoreline.
There were also six yellow cards, with the contest reduced to 11-a-side for a time.
“It was amateurish at times – certain players were thuggish,” Walker said, according to the Bradford Telegraph & Argus.
“But it was anything to get a result, I reckon, and fair play to Leigh because they came away with the two points.
“We looked good in parts and probably got dragged down by them a few times.
“We went away from the game-plan and shot ourselves in the foot by getting drawn into things and being ill-disciplined ourselves.
“It cost us and we just need to learn to deal with that sort of thing. It hurts – but it’s a long year.”