This may be the answer, but it seems extremely diffuclt to me. As far as I can follow, the solo has no rhytmical relationship with the melody. The phrases go over bar lines, use various strange rhytmical concepts, while the melody is pretty straightforward (yet unrelated to what he's playing). If Elvin was indeed singing the melody in his head while playing that particular solo, it is like writing a random story while discussing a completely unrelated subject. Maybe doable for some people, but for me it's next to impossible.Trying singing the Monk's Dream melody through Elvin's solo. Sing the melody straight without embellishing it. (I was going to write: Sing the melody straight, no chaser. But that might have confused the issue.)
If Elvin's sticking to the Monk's Dream song form, chances are he's singing the melody in his head while he solo's.