It's an interesting subject, really. I think one of the key elements to why Jons vocal abilities sound "better" on this album is because the songs are different. Maybe it was (for Jon) just the feeling that he can't sing like he did on KTF or TD, and also with the album DA in the back pocket when making a new band album. Many influences came from what at first was supposed to be Jons 3rd solo, and that was far less agressive than BJ albums are.
I know that I would doubt my own potential a little if I had both grown older and not made an album with a band for five years. But now, with an album and a tour that lasted quite some time, at least I would be a lot more comfortable in my shoes. And I think the band is in the same state, comfortable and more secure in what they do. This album is going to sound much better than everything we've heard these past years, no doubts!