Not sure I agree with that at all. He’s constantly out of position.
Not sure what your baseline for comparison is. All goalies get caught out of position. And Skinner is certainly not the fastest post to post... to me that's a lack of athleticism moreso than a lack of positioning.
Having said that, he read the game very well. He challenges shooters quite aggressively for a big-man. He's not typically off his angles and he's usually at the top of the blue paint. He has gaps that can be exposed on the short-side post because he over-relies on RVH, but you can say that about >60% of the goalies in the NHL.
When Skinner gets beat, it's usually because he's there but he has slow-limbs and/or broadly speaking lower-end reflexes. He's the type of goalie that if a guy makes his shot, it's in because Skinner won't catch up to it... but against Skinner you typically have to actually make your shot. He plays like a robot, all rote-rehearsal and near-zero ability to improvise.
You compare his positioning to another big goalie, Mike Smith for a stark contrast, and Skinner is night-and-day better positionally, it's not close. And Smith to his credit is night-and-day better athletically. So despite often being wildly out of position, Smith was capable of making saves Skinner can't dream of.
I disagree with the Koskinen comparison too... I think Skinner is more positionally sound, challenges shooters more because he is a better skater and mentally tougher (even at a young age). Neither have a glove hand to save their life.
In my opinion, it's really too bad that Campbell couldn't put things together. Style-wise he was a good complement to Skinner... in a way they couldn't be more opposite. One big, positionally and tactically sound, lacking athleticism. The other small, athletic and a big-save battler. Skinner could have learned a thing or two from vintange-Campbell's compete level. We never really saw much of that in Edmonton for obvious reasons.
One thing I agree with all the Skinner critics, is that we need another Skinner level goalie to push him. I personally don't see that in Pickard. I'm starting to wonder why we don't get a chance to see what Rodrigue can bring. Or just get on with it and trade for a Blackwood type.