Thanks for your input JJ.
I've learned a lot from the discussion here. I think I'll be returning often to read thru and soak it all in. I've realized something that I failed to consider tho. Stevie had 20 years as a professional musician under his belt before he wrote that song. Maybe this is a case of the 3 year old tryin to drink from the big boy cup HAHA! My hands just aren't big enough to wrap around this yet.
Leaving the science behind for a moment, and looking at it thru an artistic lense. This song is very emotionally driven. I imagine during the writing process he was focused more on creating that beautiful tension then making sure everything "made sense" musically. A license earned from decades of writing music. A lot of chords that have no business in the same progresion are only a few notes apart. And when you start getting into 9s, 11s, and even 13s, chords can have many other names. Ex: C13 can also be called A#M7b5. Move your pinky down a fret and it's now some other big chord (no clue folks). All this to say, the question I asked was much bigger then I realized.
I'm like a White Belt asking Bruce Lee why I can't get the one inch punch down HAHA!
I think the only way for me to really GET it is to study more songs with this kind of movement, and keep writing
That's one thing I love about music. Several ah-ha moments later I realize I've got a ways to go before I get the one I was after.
I think it is worth noting here that harmonic analysis is quite subjective (JJ already touched on this) and is rooted in the musical understanding of the analyzer. Hence, all of us classically training musicians gravitate towards understand harmony using dominant and tonic as the quintessential representation of tension and release (what Wicked mentioned in his first post). Jazz, rock and blues musicians may view things through a slightly different lens where the tonic and dominant relationship, while still important, is more apt to be purposefully corrupted or entirely circumvented.
What i'm getting at is that the relationship of tension and release is central to all music. The reason that different people, particularly when viewing music with a different cultural or temporal lens, understand harmonic relationships so dissimilarly is that, over time, listeners/composers/musicians have become accustomed to harmonic relationships that would have been jarring and tension-producing to their predecessors. This is why we have such differing descriptions of this same piece of music when we look at it as 18th century musicians (ie: classical) or as 20th century musicians (ie: jazz/blues). This is also why new composers or song-writers start to break the rules. They aim to establish a new, more aggressive tension that will capture their listeners attention in a way the old sounds, to which the listeners have become overly-accumstomed, do not.
So, Squintz, I think you might be underestimating how much you can understand. Music theory and harmonic analysis have always been things done after-the-fact to describe existing music; there were already established norms for what people heard as tension and release, someone just described and codified what they heard and call it "the rules of harmony".
With that in mind, I absolutely hear what you are saying when you describe Stevie as having 'earned a license' to break the rules; he certainly is awesome enough to get away with just about anything. However, I think that this might be the wrong way to look at it. It's not that he earned the right to break the rules, rather he just wrote music that sounded good to his sense of tension and release. Perhaps "the rules" of harmony just hadn't caught up yet...
So, don't worry what anyone says about the rules, just understand that any particular set of rules are simply a snap-shot of a particular person's or society's sense of what sounds like tension and release. They are constantly in flux. In fact, this change has only increased as more and more different types of music have become available to more and more people.
All that being said, if there is one "rule" of harmony to understand, it's that the tonic reflects the feeling of release and comfort, while everything else (dominant and pre-dominant or whatever language you want to use) reflects tension needing resolution. While many, multiple exceptions exist, I personally feel that almost all music, from about 1400 CE up until the present day, holds the tonic/dominant relationship as central to tension and release.
*** Caveat - my last statement no doubt reveals my western-centrism. I am not at all knowledgable about music from traditions other than the West.
Well, it looks like I got a little carried away with that. I can only hope that my diatribe amused and engaged! This thread has been fascinating. Thanks.