Aging? Maybe he hasnt been warmin up his voice properly before performances over the last 20 years? or just generally over stretchin his vocal chords causin damage now not allowin him to reach higher notes... and smoking cant help...lol

There a few suggestions...possibly not the 'right' reasons though.

If BJ are still goin 10 years down the line itl be interestin to see how random the setlists will be as they will be probably chosen on a bases of how well Jon can sing them rather than how good the songs are...lol