I'd need to see it again, from a different angle, I think Blind was off the field in which case:
"A defending player who leaves the field of play without the referee’s permission shall be considered to be on the goal line or touchline for the purposes of offside until the next stoppage in play or until the defending team has played the ball towards the halfway line and it is outside their penalty area. If the player left the field of play deliberately, the player must be cautioned when the ball is next out of play."