[David Chase]

Pericardial Tamponade is usually caused by injury.

The cardiac sac around the heart fills with blood, hampering the heart’s ability to beat.

To be honest, if this football player was sitting in his chair reading a book, I wouldn’t be commenting right now until more information is available.

But the world witnessed the hit (mechanism of injury) to the chest (and location).

[Steve Van Doorn]

Again. Pericardial Tamponade requires a pre-condition of fluid.
This player was on the field. He wouldn't have made it through the warm up.
The man you tried to save would've known he had a problem before the fight. He wouldn't feel very good