This is where we disagree. I like BoT just as much as the first two, and while it does seem a bit more mature and refined, something I don't mind from a band growing up, the core sound and ideas behind the songs are still the same. The vocal style is the deciding factor for me, on BoT Caleb is still using his voice in interesting ways, as a complement to the lead. Chords are there, but the primary rhythm is still bass and the two guitars are mostly just plucking out cool riffs, even if it's not as in your face as the previous albums.
On the fourth album I see the biggest shift, away from that vocal style to more standard holding notes over chords, and those chords simultaneously got more prominent and the lead took a back seat. I just have a hard time calling that maturation, when that's usually the recipe for a radio single and that sort of thing was never really in the playbook before.
I've also never been quite clear on how legit the backstory- preacher father etc- was. Has always seemed part truth, part marketing ploy to me.