The positive thing about Dean this season is actually being good positioning and come out from his area. That has been part of his main aspect to be above DDG in pecking order. Making a claim that we are in trouble is just overreacting or overcritical because you are ignoring the thing that Dean has been good at and you are using a clear 9/10 chance of goal to hide it.
Like what I mentioned and also the other poster mentioned, it's easy to say than done when you look at how quick Salah was for that goal. Even if he does as per your comment, that would still be a clear 9/10 goal, don't you think? So the point of your worry won't change.
1) Actually in situations like that, coming out too early has usually been a negative for Henderson, rather than a positive.
If you want to defend Henderson it should be on the basis that he at least tried to correct previous errors by initially staying deep, only to then make the mistake of not adjusting when the situation changed.
2) No, if the goalkeeper is in the correct position then it isn't a chance that gets scored 9/10 times (assuming you mean that literally). Obviously not. There are very few chances that have a 90% chance of being converted. It's a 1v1, not an open goal.
3) It was no more quick then loads of other situations you expect a goalkeeper to make correct decisions in. Which is partly how so many goalkeepers in that situation
don't make it that easy for the striker to score. If that's not enough time for him to physically move his body then he really is fecked, because whole swathes of basic goalkeeping will be beyond him. And even if he was stuck in place like a bollard, he could still have been more central.
You're responding like criticising him for the fourth goal is nit-picking some obscure positional error. Whereas in reality it's a glaring mistake on his part that saw him roundly criticised by those watching/reporting on the game (see all the below, for example).
There are far more examples of journalists/pundits pointing out his mistake than I can actually include in one post. Because even without getting into in-depth analysis, it's
really obvious. You literally just have to look at where he was and compare it to any of the thousand of times you've seen goalkeepers in similar situations.