I've asked about the use of "desde" vs. "de" before (https://www.duolingo.com/comment/633395$comment_id=1762754).
Here is another instance of ambiguity for me: can we not say "Es una gran caída DE aquí"? How would this be heard differently by a native speaker?
When adjectives go before the noun, some of them drop their endings:
there are seven adjectives that drop endings in front of masculine singular nouns (malo, buen, ninguno, alguno, uno, primero, tercero) and one adjective that drops the endings in front of any singular noun (grande -> gran)
Es una gran caída desde aquí appears to idiomatically refer to situations where some kind of decline is involved - it's not just that something is a long way from here, it's a long way down from here. It can be used literally, as in mountain climbing, or figuratively, as in financial situations, or socially, as in a scandal. But always with some kind of long distance down.
Didn't Humpty Dumpty have a great fall? I never thought about how unnatural that would sound in normal conversation. And Great Falls, Montana, doesn't seem like such an inviting place in this context. LOL But I agree with others that big drop is actually the best translation and should definitely be accepted. Long fall is another, more natural way of saying it, but wouldn't that be caída larga?
This explanation helped me. "As a general rule, it can be said be said that desde more strongly indicates motion from a location" http://www.spanishdict.com/answers/160756/desde-vs-de