North End looked to be heading for all three points after Scott Laird put them ahead just after the hour mark but substitute Antonio German popped up to nod home and pinch a 1-1 draw for the Bees.
"I think in the first half we were under-par and they put pressure on us without creating any big chances," said Rosler. "The two chances came from mistakes from us but I thought overall they were the better side in the first half.
"We couldn't establish any play so we tried to change the formation and it worked in the second-half. They didn't create anything and the goal came out of nothing. I always felt that we had more dominance on the ball without being able to create a clear-cut chance.
"They are fitter this year and any team who comes here will find it difficult to establish play because they put pressure on you just by bullying people and getting close to people all the time.
"We are in a good vein of form at the moment and if we can't win we have to make sure we don't lose."