Origin of "Cased"

While watching an FMX show one rider cased a jump. He broke his leg in the process. Anyway my question is how did “cased” become a term for blowing a jump-trick?

Eric

Please forgive my ignorance, but what is blowing a jump-trick?

blush

Blowing as in not completeing it succesfully.

I have no idea.

Carry on.

:o