Because given the stadium location and pitch orientation, the ball was travelling broadly north-east > south-west, and would have experienced the Eötvös effect, which is a change in perceived gravitational force caused by the change in centripetal acceleration resulting from eastbound or westbound velocity; put another way, the gravitational effect due to the vertical component of the Coriolis force. The effect would have given the ball increasing weight and made it deviate more towards the pitch as a result of increased gravitational net attraction.

Also he was running onto the ball at the time which would have generated heat in his body and caused his fingers to expand slightly. This would have resulted in them being closer to the ball giving the fef the impression that they'd actually touched it. If he'd been stood still like the current Bulls attack then it would have been clear that he hadn't touched it.

If it is a 4G pitch then it probably has those little rubber ball thingies on it to even out the bounce. Therefor it wouldn't have mattered if he'd 'fallen' over as he'd have involuntarily have bounced back up. The whole history of SL would have changed. It's like a scene from 'Sliding Doors'.