Why naive search fails

Several versions of nearly the same rule crowd the results.

Crowded results

With every version searched together, most of the top-5 slots go to versions that weren't in force on the question's date. Most are the same rule with slightly different wording or a new number.

Worse than missing

On version-change questions, naive search ranked an outdated rule above the right one 28% (15 of 54) of the time. An answer built on it states an old rule as current, with a citation.

The fix

Remove every rule not in force on the question's date before ranking. Outdated rules can then never come out on top.