Who knows if the author knew what he was doing?

The implication is that the author does not know what he would have done.

I've no idea - does the author of the article know?

The other serious problem is that the author doesn't know when to be quiet.

And while their reasons may vary, they seem to agree that, sometimes, author knows best.

It sounds like the author knows nothing about the game, just decided to believe whatever he can find on the internet.

After all, as any author knows, if a book does not sell well, it is clearly a marketing problem.

I can't help but think that the author here knows little at all about film.

I'm sure the author of the piece knows this, but it is not quite clear from the text.

What do you think of the idea that even if it's not explained, the author should know?