By the Memphis player on Karoma, was probably actually a punch to the back of Karoma. Whether shove or punch, that is what pushed Karoma into another Memphis player #97. Karoma then turned around to see who had hit him from behind. Then #97 took a couple of swings from behind at Karoma's head. Karoma turned back around to defend himself. Karoma went down and was mobbed by punching, kicking, stomping, helmet swinging Memphis players.

So Karoma was hit from behind (blindsided) by two Memphis thugs. That was the start of that particular part of the brawl. Several other Memphis players appeared to punch, kick, stomp and hit with helmets at other spots. Notably, #40 who went to the BYU sidelines and got into it with BYU players. A Memphis coach tried to drag #40 away but he was screaming taunts and insults at BYU players. That's when Nacua took a couple of wild swings at him.

Reviewing the various videos, Memphis players can be seen punching, stomping, kicking and hitting BYU players with helmets. BYU players were mainly trying to defend themselves. They fought back but were outnumbered. I didn't see any BYU players stomping, kicking or swinging helmets. Only Memphis players were doing that stuff.