I am one year younger than James. And I can say everything suddenly gets worse after 55. I am healthy, take care of myself, etc. But I see why people retire, because it becomes a full-tome job managing all the issues!. Of course, you start to notice things a little bit in your 40's, and then 50's. But after 55...it's been shocking to me. It could be that for James. The after 55 drop plus old injury could simply be it.
Aside from that, though, the last tour, I thought he did really well. I don't say anything, but being flat really hurts my ears. He has always been that way live. But last tour, he sounded really good and I really only thought it was a bit noticeable at the first concert saw in the first week. By the next week, much better, and I saw them at the end of the US tour, and he was great. Not young voice great, but old voice great. (And I was there when he did the FU, lol! These are the moments to catch live!)