closing statements, rank down, bottom ten

[KLPNO]

Hello everyone.
I'd like to ask about a sentence in a passage which is unclear to me.
The reporter named annabella is watching a report by her colleague Bill. Bill is talking with a scientist about the towers built by aliens.

Bill said, "No, not so easy at all." Thank you, Dr. Ibrahiim," then turned to face the cam. "Whatever these towers are I think it's safe to say they were not built for the benefit of mankind."
At that, Annabella rolled her eyes. As closing statements on a report went, that ranked down around the bottom ten of Bill's career.

What are closing statements and the bottom ten, and what does the highlighted sentence mean? The only thing I think I understand is that Annabella was unpleasantly surprised by Bill's words.

 

[Anglika]

Annabella does not think the Bill's "closing statement" - ending statement - is particularly good or effective. It is not that she is unpleasantly surprised, but that she thinks he could have done a great deal better. She thinks it ranks very low for quality. In fact, she puts it into the bottom ten of all the reports he has submitted.

 

[KLPNO]

Annabella does not think the Bill's "closing statement" - ending statement - is particularly good or effective. It is not that she is unpleasantly surprised, but that she thinks he could have done a great deal better. She thinks it ranks very low for quality. In fact, she puts it into the bottom ten of all the reports he has submitted.

Thank you very much, Anglika.