Of course, Pep had a game plan. Even an amateur would have a game plan. However, no plan guarantees success. They had a plan when we spanked them 3:1 and were lucky to concede just 3 goals. The best plan comes to nothing when the team concedes goals from bad mistakes. The first goal gave them confidence and additional energy, and confused us a bit. Apart from that, several players were given a chance to show they could start in the big games in the CL but didn't grab it.
Post-match analyses tend to represent the outcome as perfectly logical and erase the contingencies involved in the game. Had the referee not given them that foul, the outcome might have been completely different, and the analyses as well.