Hmmm, I'm not sure this is true. I think he's maintained in the last two decades, and I agree, that he is more consistent in his delivery than even his hey days of the 80s, which were heavily dependent on taking a 'pryotechnics' approach where he'd hold back quite a bit during verses and even choruses while punctuating at unexpected (or expected) points in the songs. Blood On Blood was a good example of that in the 80's, but I think he ultimately began performing it more consistently through the entire song in the last two decades.

During his worst years on the Slippery Tour, he was very open about the state of his voice in interviews: talking about it being shot, but soldiering on and using audience participation as much as possible.