Mike, everyone knows in birds they start in the folded position, basically laterally. Out and up or up and out. In your scenario, pteros start with the folded position, basically ventrally and on the ground. BIG difference.
Birds: jump -- upstroke during which the wing unfolds -- downstroke. Pterosaurs: jump -- upstroke during which the wing unfolds -- downstroke. Difference?
So pteros go from a complete down position at the moment of becoming airborne to an up wing position prior to apogee? That's one heckuva leap.