It will never be conclusive but what it's doing is giving some benefit of the doubt to the attacker. It's definitely giving an advantage if you look at the blue circle in this repeating gif. You can see how the circle 'cuts' through the arm at the actual offside point nearer the arm pit line of the outer sleeve. If I had to guess it's around 5cm horizontally from the blue circle wall to the white wall.
This is why the white wall looks like it's nearer the elbow as they're giving a small advantage to the attacker. Though I've never seen it mentioned anywhere but surely some people know about this? Even the old manual blue & red offside lines had an advantage. Though that wasn't widely known and people moaned about toenails, yet the advantage was 10 centimetres was in place for 4 seasons starting from the 2021/22 season onwards so bigger than a toe nail.
This 'advantage' is what I'd hoped they'd do prior to it coming in as this is an example image I knocked up years ago. The one on the left is the original semi-automated graphic used in World Cup & Champions League looking directly across the pitch. On the right, I added a thicker green line that gave a small advantage to the attacker and would now be onside.
This seems to be what the Premier League seem to have done, albeit the advantage isn't as big as the example one of 10cm. This probably explains why they now don't show the direct across view any more either. What they do now is rotate around but stop before it gets straight across the pitch and they leave it at an angle. If they did swing it right around then it may show things differently. Such as the Man City one as it could possibly show Bruno's foot just offside and it's probably the 'advantage' that's played him onside.
Here's another one that's even clearer to see the advantage. The white wall is actually on the forearm but you can see the blue circles are in the correct place starting from the arm pit line. Again it's baffling why the Premier League or whoever it is hasn't made this advantage widely known.
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