It evolved out of his old-school fakeout tope move.
He would get a guy on the outside and come running like he he was going to dive through the ropes on him, and if the guy started to move out of the way he would basically do what we now know as the 619 motion to stop his momentum before he jumped out into thin air.
At some point he must have realized that such momentum given centripetal force via the ropes could potentially translate into a powerful kick to the face, and adjusted his moveset accordingly.
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Thank you, Eddie Guerrero.
http://www.wwe.com/f/styles/photo_large/public/photo/image/2012/04/33_Moscow_04112012jg_02128.jpg