If you happen to go to sticky titled "Official US East PvP GM Rules," or something along those lines...
you will notice that one of the GM requirements is that: "you may not have over 75% psn length reduction."
This indicates that the rules have actually not been written by someone knowledgeable enough about the game, to competently write the rules.
Why you may ask?
Once upon a time, in a land far far away it happened to be common knowledge that psn dmg length reduction had a cap to it, this was built into the gaming code. Similar to DR, which caps at 50% in PvP.
It is difficult for me to remember clearly however, the game automatically caps Psn length reduction at 75% if not 50%.
So why does the GM rules say that you may not have more then 75% when having more then 75% doesn't effect anything either way?
This is just a small example of one of the many errors of the GM pvp rules which were written in an attempt to balance classes in PvP.
Further analysis will reveal things such as unbalanced dmg ratios between classes. What do I mean by this? Say a light sorc does 1000 dmg but a necro does 500 dmg. Even if the necro exceeds the GM max light res rules, and uses 95% max light res, the Light sorc will still do more Dmg then the Necro. Since a sorc can cast faster, and she is doing more dmg either way, how does it make sense to say that a necro is limited to 85% max res? It does not.
You can find all kinds of mathematical errors similar to this one in the rules.
In additional to all of the logical errors in the rules, their a numerous abstract errors. One example is that of the paladin. An effective Hdin can be made with a focus on Max Res skills rather then holy shield. For anyone who doesn't understand this, placing 2 hard skill points into, for example, light res arua, will increase the paladins max light res by 1. By spending 20 points the paladin can increase his total max res by 10. This Allows the paladin to exceed the GM Max res limit, and manipulate the GM rules.
There are several other options for coming up with ways around the rules if you think about it.
The entire GM system needs to be re-written; based on dmg ratios. And taking into account any special ability that a class may have. For example, probabilities such as weapon block, or dodge evade avoid, or ES reg rate, ect... need to be taken into consideration.
Or just say fuck it and throw out the entire GM system.