Stevie's live performance: disappointing?

[blinker12]

I saw the Mac at Nassau Coliseum this past Friday, and Stevie's performance really confounded me. In general, her voice sounded less strained than I've ever heard it _ clear, not very raspy, with a lot of the girlishness it lost in the 90s _ and yet on many songs she seemed unwilling to take advantage of the improvement!
"Rhiannon" was the most uninspired version I've ever heard _ why did she even bother? She didn't do any wailing at all at the end.
This was the first time I've ever heard "Silver Springs" and NOT gotten chills. At the end, she didn't do the high harmony over "You'll never get away...," which took away a lot of the song's power.
And she didn't go for any of the high notes during "Gypsy."
I can't tell you how disappointed I was by the latter two songs especially. They're two of my favorites, and to hear them phoned in broke my heart.
On the other hand, she did turn in wonderful performances of "Beautiful Child" _ which sounded just like it did on TUSK _ and "Landslide." And on "Stand Back," mid-80s Stevie returned for a few minutes. She did some full-throttle skirt shaking and twirling and speaking in tongues. It was nice to see her come to life, even if it WAS on a solo song.
Anyway, here's what I can't figure out: She obviously has the vocal ability to do much better on some of these songs. Why doesn't she go for it? Is she just bored by them?
By comparison, Lindsey was a ball of fire all night.