I've met several very goofy, very active BMDs.
And yes, I thought he was an aussie or BC mix from the pic in your sig.
But even if he's not a "herder," that doesn't mean he can't "herd" other dogs. Herding is a dog instinct; breeds in the herding group usually do it better than dogs in other groups, but that doesn't mean that other dogs don't do it at all. Luna - a 7-lb chihuahua - herds me when she's very excited: she runs around me, making kind of a teardrop shape, around the back of me very close to my heels and then out in front of me in the direction that we're walking, and then back around my heels again. Do I think she can go out and move a herd of sheep? No, of course not. But might she try "herding" another dog? It's definately possible.
It's like saying that only retrievers can retrieve. One of the best "fetch players" I know is my friend's chihuahua. She didn't have to teach him anything, but he'll catch and bring back a ball for so long that her arm gets tired before he does. Another friend's pomeranian is a better fetcher than most of the labs I know, and she also never had to be taught.