Games like this where without being arrogant you're expecting 4/5-0 combined with the awful weather and a very loud drum to compete with, its never going to be overly lively. it's a just get the job done game for the players and that translates to the stands. Not a big deal, you get these games at every top club at this stage. the group stages are almost a sideshow for the tourists now, it's a different crowd and you get people flashing camera lights instead of singing a song.
Also, trying to get a poznan going in the group stage isn't right, it's not something to bring out every game anymore, keep it reserved for moments like the derby day thumping and it keeps its appeal. It died out first time because of overkill, I'm all for a revival there's nothing quite like a full stadium poznan but only when it's warranted.
Fair play to their fans. Brought good numbers expecting to be spanked and at least there was some tune variation to their songs and not just monotonous drum beat at the same tempo for 90 minutes. Their drummer could actually play the thing compared to that thundering banging heard from dortmund which I can still hear now.