You can't trademark a number. Intel tried it with 586 processing chips and were told a number, or series of numbers, is not distinct. That's why the 586 became the Pentium.
Don't know about "boom" but I doubt that's considered distinct either. "Legion of Boom", perhaps, I don't know anyone who's used it before. I don't think "Doomsday Defense", "Steel Curtain", "Orange Crush" or "Purple People Eaters" were trademarked or that Dallas, PIttsburgh, Denver or Minnesota ever tried.
I doubt A&M could trademark "Wrecking Crew"? It's been title for a book and movie, a professional wrestling team, a musical group and a Marvel comics superhero group.