I just don't have the inclination to teach someone who isn't willing or is incapable on how to use statistics. It's a little like a creationist mocking evolution and then demanding a lecture.
I'll give you a very brief answer, data is data. Assuming your collection method is accurate then you have completely unbiased information at your disposal, something that's not true when we watch, especially as fans.
To use data effectively you have to understand its limitations (of which there are many but you don't have the background to understand them), and it's strengths.
So to take your example above, the league table is largely irrelevant because it isn't matching up with reality. However that doesn't mean it's without value.
Expected Goals (xG) gives an indication of the situations we've created that typically lead to a goal. The stats suggest that compared to rivals we are creating less clear cut opportunities and besides you I think everyone has noticed that we aren't creating a vast amount of goal scoring chances. So a manager can look at that and think how can I adjust strategically (or use the transfer market) to increase the amount of times we get into excellent positions. Hence why he keeps adjusting the shape and formation in behind Grabban. SL clearly doesn't think it nonsense...
What it doesn't take into account (especially in the short term) are things like how clinical a side is - Grabban when presented with the same opportunities as say me will score more goals, even with the same expected goal outcome.
Similarly it can't take into account the strengths of individual defenders and keepers in one on one duels.
There's a reason why players like Kane or a top keeper allow a team to outperform their xG.
It's also worth noting there are a number of different formulas for xG and unless you provide the one TalkSport used along with their dataset for me to interrogate it's impossible to give a more specific answer.
One small aside have you ever gone to a match and thought "we were unlucky there" - if so that's your brain performing an xG calculation itself...
Sorry if I implied that you were the one spouting nonsense - I have no quarrel with people using stats to analyse and improve performance. It was the expected goals table that annoyed me, which may have been an attachment to a stats thread on ltlf.
Data is data, but we get information through our senses. All perception is ultimately subjective. One football match contains thousands of incidents which may be hard to categorise objectively - for a start, you might need replays from different angles to decide whether a particular tackle is
a foul (with maybe a card for the defender),
a fair tackle (play on), or
a dive (booking for the attacker).
And no two refs will ever agree on every incident, so a fair play league based on red and yellow cards issued will ultimately be subjective.
Same goes for expected goals. One man's 'routine block by a defender doing their job' is another man's 'certain goal denied by fluke intervention'. Chopping reality up to analyse it is fine in theory, but how you put it back together involves value-judgements.
And the thing with goals is that no-one can be sure how the game would have gone if (for instance) Brentford's deflected free kick just before half-time had gone in. On the evidence of the season so far, Forest would have equalised in the second half and maybe gone on to win, but that's an overall observation which doesn't depend on micro-analysis.
So to record an 'expected win' for either side based on an interpretation of the number of chances created is a step too far. To build a league table from 'expected' results is two steps too far.
My opinions are no doubt influenced by working for HMRC as a customer adviser, which mainly meant dealing with a constant stream of cases or pieces of post. At some point the organisation adopted Lean, a system developed by Toyota and perhaps useful on a car production line, but less applicable to the work we did. Stats became more important, but the same people as before would cherry-pick easy cases to boost their stats.
Overnight, the office was flooded with Japanese terms and gimmicky jargon. What irked many of us was the way Lean glorified its own diagrams and buzzwords as if these were the magic keys to perfection. The map is not the territory.
So I'd dispute that my response to an incident is my 'brain performing an xG calculation', because that's whoever invented the term xG trying to persuade us that the world can only be seen in their terms.