Now that there are get_statistics implementations in a few datasources, it might be interesting to start pushing towards a filter syntax that can grab these - something like
[FIELD] > avg([FIELD])
Might do - or the function could be more general, like
[FIELD] > stat('average', [FIELD])
[FIELD] > [FIELD_AVERAGE]
Unclear, but definitely something to do while the stats work is merged.