Here’s a shot from the play where Carlos Hyde was called for a high hit against the Michigan State punt returner. I’ll let you decide if it should have been flagged, or not.
Here’s the rule you’re being asked to apply-
Rule 9, Section 1, Article 4: “No player shall target and initiate contact to the head or neck area of a defenseless opponent with the helmet, forearm, elbow or shoulder. When in question, it is a foul…”
If you’re wondering about the definition of a defenseless player, it’s “one who because his physical and focus of concentration is especially vulnerable to injury.” One of the examples the rulebook actually mentions is a kick returner.
There’s video of the play here.