On which tournaments the seeding does not follow ATP/WTA ranking?

Question

Wimbledon uses seeding which gives advantage to players that are more successful on grass courts. (Although I am not sure how long have they used seeding in this way.)

For example, in Wikipedia article on 2014 Wimbledon Championships we can read that:

The Gentlemen's singles seeds is arranged on a surface-based system to reflect more accurately the individual player's grass court achievement as per the following formula, which applies to the top 32 players, according to ATP Ranking on 17 June 2013:

• Take Entry System Position (ESP) points at 16 June 2014
• Add 100% points earned for all grass court tournaments in the past 12 months (16.06.2013 – 15.06.2014).
• Add 75% points earned for best grass court tournament in the 12 months before that (12.06.2012 – 15.06.2013)

For the Ladies' singles seeds, 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.

Are there some other tournaments which do not follow ATP/WTA rankings? In general, can organizers of a tournament make changes to seeding, if they want to do so?

Answer 1

Wimbledon is a special case and, to my knowledge, the only event at the ATP/WTA level that uses its own special "recent grass performance" seeding method.

Not many fans that follow tennis closely seem to be a fan of this seeding method because it seems to confuse more than it helps. Personally I don't mind it because it tends not to alter the seeding too dramatically. That aside, in some cases I can see why the players themselves really don't like it because it can possibly mean facing a tougher opponent than they would normally - although the opposite could be an outcome as well (facing a weaker opponent).

The main reason why Wimbledon can get away with doing this is because it is an ITF event (governed by the International Tennis Federation) and not an ATP or WTA event. That still doesn't explain why they do things that way - since all of the 4 majors are ITF events and the Australian Open, French Open and US Open still follow the ATP/WTA rankings for seeding.