Do you think its possible that Jon simply ruined it himself by over touring... not that its his fault, but it is possible.

Their third album, Slippery When Wet, shot the band to superstar status around the world with hits such as "You Give Love a Bad Name", "Livin' On A Prayer", and "Wanted Dead or Alive". The album has sold in excess of twelve million copies since its release in late 1986. On the tour that followed, Jon began having vocal difficulties. The extreme high notes and unrelenting schedule threatened to damage his voice permanently. With the help of a vocal coach, he made it through the tour. Jon has tended to sing slightly lower since then.

I read this from http://en.wikipedia.org and it got me thinking, what do you all think?