The major concern was the inability to hold onto the ball after we scored the fourth.
When Xabi, Mascherano, Gerrard and Rafa here we would have seen that game out without conceding another just by keeping the ball, controlling the midfield, playing smart and having a balanced set up. The best teams can manage all manner of game situations and we just can't.
I am not sure if Klopp really believes in controlling the games using Xabi , Mascher style midfielders. It might be something we need to get adjusted to. I have not watched a lot of Dortmund but some of the games in their champions league final appearance run were not too dissimilar to todays game.
He is more Ferguson than Rafa or Mourinho. Rather than customizing a defense to neutralize threats, I think he is all about put enough goal scoring attacking players on the pitch who can press like crazy, whip the crowd into a frenzy and create a mental environment with the crowd and the team feeding off each other. Irrespective of what he might say about the goals conceded I think he loves the chaos. If we win every game 1-0 he might get bored and quit.
I do know he had midfield players like Gundogan, Sahin, Bender(?) at Dortmund but I am not sure if he ever used them the way Rafa used Xabi, Mascherano.