An overutitlized word, a lot of journalists write things like dropped to
make their writing sound tougher. If a guy hasn't landed on his head, or fell 2 or more storeys against his will, he wasn't really dropped, he was
just knocked down (if he went all
the way down).
Quarterbacks who
got sacked didn't get dropped (no matter how many yards they
lost in the process), they got knocked down. The same applies to a guy getting knocked down in any other
sport.