Question is if contact is made after the ball is out of the pitch, is it still a foul?
From the slowed down replay it is clear that
1) Bill Cosby dives
2) player touches ball
3) ball exits pitch as contact is made.
The only technicality is it is a challenge from behind.
But breaking it down it is a clear case of simulation, and not diving over a tackle to avoid contact.
This referee gave three penalties this match (one for Sociedad). He had to give Madrid two to make up for the one given to Royal Society.