I don't know who needs to hear this but you can't reliably use the average position metric in Google Search Console unless you are looking at a specific keyword.
Looking at a site overall and seeing average position declining doesn't actually mean you have a problem.
You might be getting new low rankings that are on high volume queries. That would make it look like you were doing worse when, it fact, you might be doing better overall.
@ipullrank Oh don't get me started about how you rank for appearing in an image pack.
Every now and again I have a client who suddenly gets a massive amount of impressions for 'reverse uno card'.
Rank skyrockets and CTR plummets.
@laurentbourrelly @johnmu @ajkohn @ipullrank
Mouse rage clicks.
@johnmu @ipullrank Not weighted average position. No, no, no, no. That would just be another thing I'd have to explain.
Much of this isn't a problem with the metric but with people's lack of understanding of data analysis.
Outside of that, more clarity on what is included as position/rank would help. Image carousel? People also ask?
Biggest ask would be to create filters for those things. Remember when you briefly showed featured snippets?
@johnmu @ajkohn The first step is giving more visibility to the explanation of how average position is counted. Too many people assume that avg position is counting straight down the page so they compare it to a ranking value which does count straight down the page.
A new metric will just confuse things further.
AJ Kohn
MyCool King
John Mueller
LaurentBourrelly
Simon Cox 
Stephen Sumner