As far as we can tell, this time will come where United have a more well-rounded GK who fits the overall approach that EtH wants to play. It was evident at Ajax and it will be more evident at United and we're seeing why. For the time being, we will only go off what we see and that's DDG making big saves when it counts and he's doing what he can (it's limited) on the ball.
United's xG for today's match was lower than their goal output, so they were more clinical and/or ter Stegen let in at least 1 goal that he shouldn't have...that is pretty clear.
I totally agree that United will need a new GK that is confident and aggressive on claiming high balls/crosses, is much better with his feet for all things passing, and is comfortable going 1v1 with a better penalty record. But with that new player comes a lot more scrutiny, pressure, and mental stress. Also, will their reflexes, positioning, anticipation, catching, calmness, and ability to make saves after doing nothing of note be the requisite level? Let's hope so. But we should all understand and except that GKs will always have mistakes in them and that is evident the more they are involved in the general outfield play.
But we continue on with DDG and he has his flaws like the overall squad, but it's not that bad compared to the gaping hole at CF and secondary scorer to Marcus (i.e., CF).