He has been really unlucky. I mean sure, more often than not you can find small mistakes to pin-point when analyzing slowmotion/freeze-frames of the situation and then go on to argue the keeper could've done this or that, but let's not kid ourselves here - many of the goals he's conceded have been insane, and in the rest he hasn't exactly gotten much help from the defense in front of him.
Yes, he could maybe have scrambled and punched the ball away, but it didn't help that Mathieu, who stood in the way of his line of sight and was responsible for marking Papadoupolous, suddenly thought he was playing dodge ball and cowered away from the ball. Or against Las Palmas when Mascherano suddenly decided to "clock out" mentally while running with the ball in his own half and get dispossessed, with the following shot getting deflected.
Problem here is that you can argue both sides quite easily. There are definitely things he could've done better in many of the situations, but he has also been very unlucky in several of them, and he is definitely a better keeper than what he has shown these past weeks. Personally I still feel safer with Bravo and think he's currently the better keeper, with better reflex saves near the line, better command of the box and overall better positioning, but Stegen has tons of potential. For instance his talent for sweeping and distribution of the ball is extremely rare. I really believe he's going to be our main goalie for the future.
His bad luck is bound to turn around soon, and with that his form and confidence will go up as well. When in form he's good enough to be our main GK as it is, I mean the guy played very well last season and made some very noteworthy saves that helped us towards the CL trophy, with his performance against Bayern and that epic save that won the "best save award" coming to mind, so let's not act as if he was just a passenger either.
My 2c...
