For me, it's not about the players and whether they are in or out of form, or whether they still have the desire etc (although these things are of course a factor).
But mainly it's about our tactics. Someone else said that we play without taking enough risks and I totally agree with that. It's the main reason we are pretty average (at best) when KDB doesn't play: He's the only one who is always prepared to play first time balls, to try adventurous forward passes, to have a shot. The rest of them more often than not, slow the game down, retain possession and pass it around waiting for an opportunity.
An opportunity with decent opposition, that never comes. I get the impression we could play for 3 hours against the better defending sides and still not score. And of course when we finally make a mistake, they pounce and the best sides take advantage and we drop points again.
This is no system for winning the league or the CL. Carry on like this and we will win nothing. It MUST change. We have to start being more attacking and more direct. Get the ball in the box early and calamity often ensues, resulting in a goal. Pass it around aimlessly for 5 minutes and the opponents get organized and chances are few and far between.