Billie's Vocal Change

Is anyone else surprised how much Billies vocals shifted in such a short time around 2009?

Imo his voice peaked 2000-2006, which makes sense given that was his early 30's. I think his vocals are pretty similar from 1994-2006, but the way in which he delivers them has a slightly different style on each album.

However his vocals completely change around the 21CB era.

The octaves he's most comfortable singing in completely shift, and he becomes much more comfortable singing in higher octaves with a more nasal driven voice, which is something that is still accurate to the present day.

I can't really think of another vocalist in this genre that's vocals have changed as instant as Billies did circa 2009. I definitely prefer his pre-2009 vocals, but still think he sounds great on later material. Just shocked by how much changed in an instant!