The main reason historical meetings between two clubs predict so little is simple. The teams that produced those results have largely been replaced.
Turnover is faster than it appears
Squads change every window through transfers, loans, retirements and contract expiries, and a typical club replaces a meaningful share of its first-team minutes each season.
Across three seasons the overlap between two versions of the same club is often smaller than the overlap between two different clubs in the same league.
The badge provides an illusion of continuity that the team sheet does not support. Two meetings separated by three seasons may have one or two shared starters, and often none at all in the forward line.
Coaching changes compound it
Managerial tenures in most major leagues are short, so a record spanning several seasons usually crosses at least one change of coach at each club.
A new coach alters formation, pressing height, build-up structure and selection policy, which changes how the team performs against a specific opponent.
Both variables moving together means a historical meeting may share neither the players nor the plan with the fixture being previewed.
What survives turnover
Some things do persist. Recruitment departments have preferences, and clubs that consistently sign a particular profile of player retain a recognisable identity across coaches.
Stadium characteristics, travel distance and supporter culture also persist, and they contribute a small but stable component to home advantage.
These are the only parts of a long head-to-head that have a claim to relevance, and none of them concerns the results themselves.
Recent meetings are a different case
The last one or two meetings often do share personnel and coaching with the upcoming fixture, which makes them worth watching rather than counting.
Their value is in the detail of how the match unfolded rather than in the result, since a single result is almost pure noise.
Where a coach solved a specific problem last time, the question is whether the opponent has since addressed it.
How to weight the record honestly
Discount meetings sharply as they recede, and stop entirely at the point where both coach and a majority of the starting eleven have changed.
For most fixtures that leaves two or three matches, which is not enough for a record and is enough for context.
Anyone quoting a decade of results is describing history rather than the teams about to play, and the distinction is worth insisting on.