Further nitpick: the page is very misleading. Audio compression has different targets, a crucial one being music.
The Opus official page has comparatively little test references for music, both of which are at 64/96kbps for AAC [1-4], which is significantly below the general audience listening standards (160+ kpbs).
This implies that the red line on the top right of the first diagram is literally made up.
Until further blind listening tests are performed, generic conclusions such as "Opus outpeforms the competition" are unfounded.
> It attempts to summarize results [...] and (when no data exists) show anecdotal evidence
This is borderline offensive for people who are serious about researching music quality. Any anectodal evidence [in this field] is garbage.
[1] http://listening-tests.hydrogenaud.io/igorc/results.html [2] https://people.xiph.org/~greg/opus/ha2011/ [3] http://listening-test.coresv.net/results.htm [4] http://opus-codec.org/static/comparison/GoogleTest1.pdf