High turnout - R +13
Low turnout - R +18
Normal turnout - R +4
Isn't that peculiar. I would expect a more linear change along the turnout continuum.
I'll try to intepret it:
Low turnout = Dems staty home in fit of depression / GOP turnout stays normal. (R+18).
Normal turnout dutiful Dems show up closes the GOP gap to +4.
High turn out: While the dutiful dems show, the GOP votes like it's a presidential year making it +13