the.com/slump

means A sustained dip in performance or activity, especially one that drags on without a clear cause.

from Slump shows up around the 17th century as a word for sinking suddenly into mud, water, or snow — the sound itself is a thud, a squelch, likely imitative like 'thump' or 'bump.' From the physical sense of sinking or collapsing, it slid naturally into the figurative: markets slump, spirits slump, batting averages slump. The economic sense ('a slump in sales') took hold by the 1800s and the sports sense followed the same path — you're not broken, you've just sunk into a hole nobody can quite explain.