What adds more interest to this IMO is it seems a lot of "correlations" we had been very familiar with have diminished over the past decade-plus as well. Now, the easy answer here is that is just a product of increasing our sample size (data set). This is likely certainly a factor, but how strong of a factor? But I suspect something else is going on too...and the way to come to that conclusion is when you break everything down into how we understand things and basic principles and you're getting results that don't make sense.
also, if I understand correctly, the correlation is geared more towards the evolution of the AO? Lots of influences on the state and evolution of the AO, especially stratospheric processes.