Is how you present more important than what you know?

No, speaking in public about stuff you know nothing about is called "bullshitting". You may be able to get away with it if your audience is ignorant, but as soon as someone who does know the subject begins to ask you difficult questions you will be quickly exposed as a charlatan.

However, if you know your subject and are the world expert in it but can not communicate in public this too does not help. Sometimes clever people are not good at public speaking but they do have the option of communicating effectively in writing. Ultimately ones written legacy is more important.