It's purely rhetorical but - the specific 90% figure aside - it's fairly straightforward that not everyone can be the best. Everything else is just figuring out

It's purely rhetorical but - the specific 90% figure aside - it's fairly straightforward that not everyone can be the best. Everything else is just figuring out what sort of distribution you have. In many fields the definition of "crap" depends, after all, on what the rest of the field's output looks like.