Well, I play jazz a lot and Mark's music just blows my mind every time. He certainly studied a lot of music theory in the mid of 80s. He also suggested a book called "Mickey Baker' Jazz Guitar", do you see it? Hundred pages of hot and deep music theory stuff even without any TAB, only with standard notation. Mark uses Dorian Mode a lot (B Natural in Why Aye Man, G Sharp in Je Suis Desole), Mixolidian Mode (A Natural in Calling Elvis, G Natural in Vic and Ray) and so on. BUT, it's just the names for certain sounds. And most of the songs in Ionian Mode actually, which is standard Major scale. You can easily doesn't know what the hell Dorian or Mixolidian Mode is, but knows it really by heart. All those guys also known as "he was born for music and all" guys can do it that way. But anybody can learn this, anybody can improvise, anybody can write music, you just should learn how to do it properly, step by step.
And Dorian Mode is just simple minor scale with sharp 6th, I noticed certain notes from MK songs above. Music theory is really, really easy stuff once you know how basic major scale constructed. Not only easy, but very interesting. Scales, arpeggios, chords, chromatics... oh, I love all that stuff.
I really want to do some covers of MK. But actually it takes years to understand and learn how to play MK songs properly. Even be-bop is easier, not kidding.