Wimbledon's seedings have historically not followed the world rankings exactly, unlike the other majors. The departure existed because grass rewards a specific skill set that a year-round ranking understates.
Rankings average across surfaces
A world ranking totals results from clay, hard courts and grass in whatever proportion the calendar happens to provide, and the grass block is short.
A player who is excellent on grass and ordinary elsewhere will therefore sit lower than their grass-court ability alone would imply.
Seeding purely by ranking risks pairing two grass specialists in an early round while an ill-suited player receives protection.
The adjustment used a published formula
For many years the tournament applied a stated calculation that added weight to recent grass-court results before ordering the seeded players.
Because the formula was public, players could compute their own seeding in advance, and the process was not a matter of committee opinion.
Transparency mattered here, since a discretionary system would have invited persistent disputes about favouritism and national bias.
The two championships have differed
The women's championship has generally seeded by ranking, with a committee able to intervene in unusual cases rather than applying an arithmetic adjustment.
The men's championship carried the grass-weighted calculation for far longer, reflecting a view that grass altered men's tennis more sharply than women's.
The asymmetry drew criticism over time, and the tournament has since moved the men's event towards straightforward ranking order.
Seeding changes the shape of the draw
Seeds are placed so they cannot meet before a specified round, which means the seeding order determines who a leading player faces and when.
Moving one player up or down a few places redistributes opponents across an entire half of the draw rather than affecting only that player.
The effect is largest at the boundary, where being seeded at all is worth far more than shifting several places within the seeded group.
Convergence has narrowed the case for adjustment
Court preparation and ball specification have made grass slower than it once was, reducing the gap between grass specialists and all-court players.
With the surfaces closer together, the world ranking predicts grass-court results better than it did when the formula was introduced.
The special calculation answered a difference that has partly closed, which is the clearest explanation for its quiet retirement.
