David Nixon. Cameron Jensen. Bryan Kehl. Leon White, another great, was very soft-spoken and humble off the field. KVN seems very chill in his interviews, etc.
I get what you're saying about an aggressive, "I don't care," mentality going hand in hand with playing linebacker. But the idea that anyone that played these positions at a high-level is a loose cannon or meathead or whatever is overplayed.
There's no shortage of guys who were great, aggressive ballers but whose public or private personas aren't anything like Pop/Derrick. Especially if we're talking BYU guys. They were able to flip the switch on the field and/or in competitive situations. Or maybe they just did what the game required without flipping a switch at all.
Plenty of exfootball greats are as you say, but it's a much more diverse group with an array of personalities.