The vocal coach has a lot to answer for!
 

https://www.youtube.com/watch?v=-9sFdoAW9sM

How great does Stevie sound here? That vocal coach she worked with in preparation for The Dance did her no favours. The drop in quality in her voice between this and the Enchanted tour in 98 is shocking.

Carlos is such a great guitarist too! His "Rhiannon" solo here is amazing

Here is another belter!

https://www.youtube.com/watch?v=MwPZOhrsMDk

The biggest change happened between the 1986 RAL tour and the 1987 Tango tour. It's like she was a different person singing. She rarely pushed herself vocally or even physically after that, with a couple of exceptions like the SA tour and the outdoor clips above. Blame Klonopin I guess, but she was off that medicine for subsequent tours and her more lively voice never came back.

Oh I dunno, Mirage to Wild Heart is a pretty big change. Her vocals on the Mirage album are so strong, infact my favourite performances of her Fleetwood Mac output, but the Mirage tour vocals and then onto Wild Heart was a big deterioration from the Bella Donna tour and recorded Mirage vocals.

I felt that her voice changed for the worse sometime during the enchanted tour. I guess as you age the voice changes, but I wish she at least had the vocals she had during the Street Angel tour.

She was great on the Street Angel Tour and to think I only paid $17.50 for first nine rows.. Now we get yelling and bellowing for over ten times that amount.

Smoking took its toll.

I guess what I mean is the amount of effort she seemed to put into her singing up until the 1987 tour. She really throated her vocals, adding bellows and barks, and the vibrato was still there. Maybe she wasn't singing 'right' but it made for a very entertaining show. Even if she couldn't sustain the vocal and it broke into a howl, she still tried. From 1987 on, she seems to sing from a different place and fakes the sound of prior vocal style. Look to her Edge wails, and how different they are. I don't know, she seems to have gone from singing in her throat and chest to singing somewhere from her upper palate. The exception to this was the 1994 tour, when she sometimes (but not always) went back to the more expressive vocals. She did not do the crazy dervish dances though, but at least we got part of the old package.

I love “Twisted” from this show. So wonderful to hear her singing a (then) brand new song with such passion and commitment. It also happens to be my favorite of the many different arrangements we have of that song! Her immediate-post-Klonopin vocals 1994-1996/7 are some my favorite. Not least because it was such a relief to hear that she could still sing after the slurred, deflated vocals of 1988-1993.

She sounds great.
Quality of her voice has only marginally declined.
What really happened is she has lowered the keys of most if not all songs.
She was a mezzo-soprano. She is now contralto.