Are there any rules concerning giving players differents seeds from their ranking ?
In the men's tournament there are grass points, which are added to ranking points and the sum of those 2 decides what seed a player gets. So it's objective and perfectly predictable.
Is it the same with the women or can they do whatever they want with the seeds ?
From the Wimbledon website
For the Ladies, the seeding order follows the ranking list, except where in the opinion of the Committee, the grass court credentials of a particular player necessitates a change in the interest of achieving a balanced draw.
The simple truth is, there's no reason to move anybody. The 2008 and 2009 finalists will be the #1 and #2 seeds anyway. (They only go back 24 months in determining grass point for the en, so I doubt they'd look further back than that.) Last year's semifinalists are ranked #5 and #20. Should Safina be seeded #16? And if you aren't going to move Safina, who do you move.
Sharapova? 230 grass points last year.
Henin? 0 grass points last year.
Clijsters? 0 grass points last year.
The one player you might seriously consider moving is Na Li. 390 grass points last year. But adding that to her total wouldn't get her the #8 seed, and any move less than that doesn't matter.
Wanna drop Schiavone down? Hard to make that case. She had 660 Grass points last year, and and made the QFs at Wimbledon.
The ranking do a good job of determining what seeding should be. Lots of people thought Henin should have been given a higher seed at RG. But unless she was seeded #8, she could have drawn Stosur in the 4th round anyway. The players seeded #17 - #24 all have a legit shot at making the final 16. No shock there. In fact, a 5'5" all court player who was seeded between #17 and #24 DID win Roland Garros. Just not the one the 'experts' expected.