Last season?
No - we weren't really missing anything offensive as the usual setup in a 4-2-3-1 war pretty good even with a Coman and Costa (so Costa already was on the decline for us and Ribery was just starting matches after a long period out) - we were still missing a really fit defense - but that was not the problem.
Our problem was that we were like usual going into the away leg with only three offensive players - especially as just one of them in Lewy was strikerlike. Pep - as he often has told before - has the away tactic of controlling a match. And - as often that does not function against very good offensives full 90 minutes. In his ideal thinking - yes - in reality not. There is always the odd mistake. And he accepted and knew that we usually were pretty toothless offensively that way.
That is my main critics against Pep. That brought us onto the backfoot a couple of times before. Donezk and Porto, even Real and Barcelona the seasons before. The away goal is so important and a 0:1 against top teams mean that you have to open up at home and the opponent sits back - and a goal against means that you have to score 3! We might be able to work it out against teams like the mentioned Donezk or Porto - but against very good defenses and teams with a great counter attacking thread it does not work.
There is two factors in it - one is the third midfielder for Müller - one is Alonso for ball control instead of a more sweeper like no. 6. No - somewhen mentioned him before (I had it connected with my name in the Alerts!) - Alonso was never a problem during the Pep years. He was instrumental for Pep's idea of play and he was well whenever his other midfielders were giving him options. All players have their weaknesses. With Pep that was still okay - with Ancelottis fullbacks that often had to play very high and did not play inverted the more defensive sweeper like 6 would have been mandatory when I would have been asked.
At the end we could have made it against Atletico if Müller would have scored the penalty - but that is even made with a questionmark as Griezman did not convert his either and Atletico had scored another goal in the return leg.