No problems. I will try to tailor my reply to each point as they are interesting points on each.
The Xg does suggest we are sutainable. Thats the point here. The Xg has us likely to be in the top 3 or 4 teams in each category, which is normally indicative of a side that wins the league. Xg information really validates the idea that it is sustainable.
Emery Arsenal is the opposite comparison. They outperformed their Xg, but they have 2 world class finishers, Lacazette and Aubamyang. So it wasn't ll luck for Arsenal, it was they had two players who were great finishers.
I agree with your point, which I think is that Pickford as a goalkeeper is such a lag on Xg he pulls us down. At present though he seems to be pulling us from top 1/2 in the league to probably around the top 4-5. That would be my counter here. I think Pickford will cost us too, but we are falling from a higher base re Xg as things stand.
(Edit, we are actually 2nd on goals scored, 3rd on goals conceded and 2nd overall on points from this site
https://understat.com/league/EPL ).
On the 2nd point, A lot of those years have an existing top 4 that wascut off from the league. That came downa bit when it went to 6, and at present seems to be coming down more year on year. Early indictions do not give rise to the theory that there will be 4 distinctive sides stronger than last season. But even if we met in the middle, and said the to 4 will be between 65 and 72 points, its hard to argue we are not actively in the hunt for that now
I did some research last week, looking into sides who won their first 4 games over the past 25 years. 15 of the 17 finished in the top 4, and most finished in the top 2. We have done it 3 times in the last 60 years and have finished 1st, 1st and 4th. Statistics would indicate we are in the mix.
The 2 sides that didn't were Watford (18), and Sheffield Wednesday (96) and both of them lost their 5th game and went on a run of 1 point from 4 games.So we have already avoided one of those metrics, and short of losing the next 3 consecutively will have avoided the other measure. Again it doesn't mean we will finish in the top 4, but we can legitmately say we are in the hunt.