Imagine an elementary school teacher told you that many of her students had failing grades, so she had implemented a new reading curriculum.

If she told you that afterwards the failing grades had "soared", it could easily be read either way:

- The (previously failing) grades had increased, so the program must be working very well.

- The percent of grades that count as failing had increased, so the program must actually be terrible.

"Falling" means that something goes towards the earth. "Soaring" means the opposite. "Grades soar" means that grades went up "Falling grades means that grades are going down". "Falling grades soar" is just meaningless writing.