Having been overrun in the first 45 minutes of their defeat to Bolton eight days ago, Berg saw Rovers turn in another lacklustre first-half performance during last weekend's 1-1 derby draw at Burnley.
"The players dealt with the Burnley game okay but maybe we were caught a little bit in terms of not settling down and playing football as we would have liked to," he said.
"I know we changed (formation) a little bit in terms of how we wanted to play so maybe that's why the game ended up being how it was in the first half, because we played a little bit differently to what we're used to.
"We got caught a little bit too much - we didn't find the right balance between when to be direct and when to keep it and use the spaces.
"I think that is always the difficulty sometimes for players to find that right balance but that is something we'll work on."