[elektronaut]

Phrygian is quite common in metal, along with phrygian dominant. Great scales for dissonance and tension.

Functional harmony kind of goes out the window once you stray from the major/minor modes anyway. You have to lean heavily on the root to maintain the tonality, or else the perceived key center tends to shift.

[rumcajz]

Ah, I haven't been aware of usage of phrygian mode in metal music. Maybe that's what skews the ratio of Emaj/Emin towards the latter?

[jeeceebees]

The author notes that the analysis is based on 1300 songs from the Billboard top 100 in the last 2 years.

I think it's safe to say the effect of metal songs using phrygian is negligible.

[rumcajz]

And the phrygian used in metal has modified major third (G# instead of G) which, again, results in E major, not E minor chord.