Think it is very harsh to call PSG a midfield-less team. The midfield along with the defenders did what very few team succeed with when facing Barcelona - they played their way out of their pressure and thus putting Barcelona on the back foot. You don't accomplish that with a midfield-less team.
All in all, you have to think that this really was an opportunity missed by PSG. They had a real chance of knocking Barcelona out, but due to wastefulness in converting the chances they beautifully created it wasn't to be. They'll be kicking themselves I reckon.