"You've got to be ruthless and we weren't," said McCarthy, whose team were leapfrogged by Wigan in the Sky Bet Championship table.
"There were good saves, good blocks but I think we should have scored.
"We let them off the hook with the chances we've missed and it sounds like a broken record.
"We've got be more clinical, ruthless - whatever you want to say - we had enough opportunities.
"We've got the points we have and we are where we are because we've not completed the task that we should have done."