Most proposal problems are operations problems, not writing problems. A stale content library. Review gates nobody enforces. Decisions made too late, by people too far from the bid.
I've run global proposal operations for a Fortune 50 technology company and built teams from nothing across the US, Costa Rica, Europe, and India. Before that, federal work, where a compliance matrix teaches you quickly that process beats prose.
The half I'm good at is the unglamorous one. Gates people actually keep. Content that's current. Someone senior in the room when the bid/no-bid call gets made.