It's now been almost five years since Richie left the band. JBJ could still sing even the harder songs - such as Always - pretty well in March '13, as is shown by this video:

https://youtu.be/H0d5Tkh4jck

However, within a few weeks' time after Richie's departure and Phil stepping up, Jon started to lose the control of his voice. The decline was subtle at first...

https://youtu.be/2TgOxMyhGSc

https://youtu.be/jxnTQaPUJV0

Then it became noticeable:

https://youtu.be/xo_QuKXPDUk

Then, just for a couple of days, Jon seemed to be getting it back again:

https://youtu.be/9h39nFY1lY0

https://youtu.be/VNtLjw1DKsM

But guess what happened then, in only a few months? Yep, Jon lost not only the rest of his voice, but also his stage presence:

https://youtu.be/L32FQUA-VJc

He seems to not have gotten either of them fully back (although the Sao Paulo show was way above par, I have to agree with Walleris there and admit that his "vocal renaissance" won't be sustainable on a regular fashion at least, whereas his stage presence actually could if he regained some of his confidence) even now that it's almost 2018:

https://youtu.be/Q7OOexWdsrU

How the departure of a band member, no matter how dear and close, can have such a long-lasting negative impact on any experienced performer's confidence and overall abilities of doing what should be routine by the time is really confusing for me. Joe Perry was out of Aerosmith for a couple of years and it didn't ruin Steven's voice (or other performing abilities for that matter).

What should Jon do to grow his confidence and get his overall happiness back? I mean, nowadays he seems exceptionally serious being interviewed as well.