His open-eared approach, which mirrors that of these other singers, has led him to some of the same places they discovered in their own music. I came across Jimmy Scott later, since he's had his comeback. I would compare him, to a degree, to Billie Holiday, in the looseness of how he approaches a melody, in the way he can just leave the melody and create a new one that seems like it was always there. It's because I sing most things in their written key. That comes from playing tenor.
Singers are always transposing things to 'their key', bur hornmen almost never do that.
We play the song in the key it's written, and it provides a lot of variety. Sometimes it lays at the bottom of the range, I'll be singing up in my register, and I have to treat it differently. I'm not afraid to use falsetto - or even to sound ugly at times.