First of all, Greenbull didn't take down the entire crew, the flying six, numbers and Jack weren't there. Second, King didn't have his sword with him while queen didn't have his plague. Third, the beast pirates are the weakest Yonko crew (which I've been saying for three years), he can't do that shit with other crews. Try to do that shit with Luffy, Sanks and Blackbeard's crews, Greenbull would be handed Ls left and right. And last but not least, that Scene was mostly for hype, Oda didn't even show what happened there, Oda just had to hype up Greenbull somehow, and beast pirates were the only available target. Imagine if Greenbull was injured or pushed to high diff by the beast pirates, that would dehype Greenbull pretty badly. So with all do respect to all Admiral fans, it was a necessary sacrifice for Greenbull's hype, in any other situation he would be pushed at least to mid diff, let alone if he was up against someone more powerful like Shanks' crew.