Evans, Fournette, and Arians were the main culprits, and as much as I hate Brady he was just jawing back and forth with Lattimore, which was fiery and contained some 4 letter words I'm sure but ultimately just trash talk.
The way I saw it was Brady and Lattimore trash talking, then Fournette comes in and shoves Lattimore, who of course is going to shove back, and then Arians (who was a main instigator, IMO) eggs Evans on to get in there and do something, so in comes Evans and totally blindsides Lattimore, who is just doing the typical tie up and wait for the refs to come break it up routine with Fournette. Then all hell breaks loose.
Had Evans not come in the refs separate Fournette and Lattimore and the game goes on.
Arians is a punk with a big mouth who came down from the box to "help" by stirring up trouble and succeeded. Arians is the opposite of a calm, collected leader. Instead, he is an instigator, escalator, and trash talker "tough guy" himself.
Evans deserves the suspension, and Arians deserves criticism as well. The role of a coach there is to deescalate and get your players under control. Instead, he threw gas on the fire.
Yup, it's happened a couple times now. The blindside/cheap shot part is the worst. Total coward move.
I would bet most out of control brawls in the NFL are due to cheap shots. Fournette, brady and Lattimore were just going to stand there and yell at each other until they were parted, with some decent shoves between Fournette and Lattimore.