GPOMJW: Body Lean
The guy really does look like he’s flying.
There’s just some sort of balletic grace to his movement that can’t be explained. Unless you’re me. I think it’s his body lean.
Most dunkers, because they’re usually running toward the basket, drift forward as they jump. MJ, though, appears to jump on a diagonal. It’s his upper body leaning forward. That movement brings his legs behind him (which twist and torque for added beauty), and provide a contrast to his arm, which windmills against his momentum.
His body lean also helps create the illusion of extra hang time. Jordan’s launch allows him to dunk at what appears to be the peak of his flight path. He’s not falling to the court as he scores. He appears to be reaching his zenith.