True, and also true about the south based blocks linking up with the SE ridge - that’s a pretty new phenomenon.
I personally like numerical index values only because they’re easier to analyze in Excel or run a machine learning model on (one of my ongoing side projects btw). Not easy to do that with spatial 500mb maps, but it’s important to use those maps to validate any conclusion drawn from analysis using numerical indices.
I’m also realizing that the NAO shouldn’t even be looked at in isolation, but in combination with the AO and other indices. The deviation of the AO from the NAO in and of itself should be a clue that something amiss is going on.