I posted this in the match thead, but the only justification for Lucho setting out the team wrongly last night I can think of is this: Barca came into the game in form, PSG seemed terribly out of form and lacking a goal threat with their lack of goals up until now. In hindsight, the correct way to approach the game was more cautiously and with more control of the ball. But given the context before the game started, it is understandable to some extent why Lucho would think Barca had a chance of rolling PSG over and keep the set-up they have been using on and off in La Liga, where it has been so effective.
That's not to say Lucho should be absolved of criticism. It was a terrible performance last night and the squad he has should be enough to beat a weakened PSG in their own stadium. IF he makes the same mistakes in Barca's next tough match (Real Madrid at Bernabeu), then I'm afraid this looks like another Tata season in the making. And he'll deserve all the criticism coming his way.