Ellipsis fails when essential participants or events become unrecoverable. It succeeds when neighboring context supplies the necessary links and the narrative remains intelligible.
Effective concision: the unstated matter is recoverable and the intended meaning survives.
Defective compression: missing information causes a substantive loss of clarity.
A full explanation should identify what is omitted, how the context supplies it, and what communicative benefit the omission yields—not merely announce that “something is missing.”