A day after Schzeny signed for Barca as a repalcemet for Ter Stegen, he was asked by an interviewer how long it would take him to get match ready given he had retired a few months earlier. He responded that he needed just 2weeks to get back in physical and mental shape but he would need about a month to build his instincts back to a certain leve to track and react to the movement of the ball. According to him, footballers lived on instincts as they have to react and decide within nano seconds on the pitch and even more for keepers. They need to predict the projection of balls even when there are deflections, according to him.
A double slo-mo of that goal is enough to show that Raphinha had started the run towards the goal as soon as Martinez flicked on the ball from the edge of goal post. Curbasi's shot an keepers touch were in quick succession and he reacted on instinct to ensure it was a certain goal. You would see it differently if you were in the stands or watching from your TV.
If he had hesitated and that ball somehow did not go in, it is this same set of purists that would call for his head. C'mon man!!!