Bonnar is tough enough, big enough and will be motivated enough that if Anderson wipes him out Forrest-style, it won't be a case of "of course, Bonnar is shit" but "wow, nobody fights like Anderson."
And if Bonnar puts in his career-best performance and Anderson is off his game, he could be a live dog.
Plus, no matter what, Bonnar will step up and give it his best effort. He'll be in Anderson's face trying his best to win the fight, until Anderson stops him or 15 minutes are up. And that's something you can't say about quite a few of Silva's opponents.