I wanted to clarify some common mistakes I see people make when creating gnomesequencer macros for Prot warriors. The issue that cripples DPS is a misunderstanding of how exactly gnomesequencer works. Gnomesequencer does not necessarily prioritize skills, rather, it uses them in a cycle and in order to get the best DPS possible, you need to maximize your chances of using the right skill in the right priority. Let me give you some examples of what works well and why many current macros are sub par.
A sequence that works well:
'/cast Shield Slam',
'/cast Shield Slam', <--- Shield slam prioritized over revenge,two casts give it a greater chance of being used before revenge
'/cast revenge', <---- Revenge prioritized over devastate
'/cast Shield Slam',
'/cast Shield Slam',
'/cast Devastate',
'/cast Shield Slam',
'/cast Shield Slam',
'/cast Victory Rush',
'/cast Shield Slam',
'/cast Shield Slam',
'/cast [combat] Storm Bolt',
'/cast Shield Slam',
'/cast Shield Slam',
'/cast revenge', <--- revenge again prioritized over devastate because it must be triggered by GS before and after the devastate usage
Notice that shield slam is prioritized over everything because after every attempt to use any skill, it will attempt to use shield slam twice. Revenge is prioritized over devastate because it will attempt to use it before and after the devastate attempt. This sequence combined with a good pre and post macro will give you the best chance at maximizing your DPS with GS.
Now lets look at what a lot of people are using and why it does not work:
'/cast Shield Slam',
'/cast Revenge',
--'/cast [combat] Blood Fury',
'/cast [combat] Bloodbath',
'/use [combat] 13',
'/use [combat] 14',
'/cast [mod:shift] Shield Block',
'/cast [mod:alt] Heroic Strike',
'/cast Shield Slam',
'/cast Revenge',
'/cast Victory Rush',
'/cast Storm Bolt',
'/cast [combat] Dragon Roar',
'/cast Devastate',
'/cast Shield Slam',
'/cast Revenge',
This is one of the better GS macros because the creator prioritizes revenge before and after devastate. However, it will generate less DPS because shield slam is not prioritized over revenge in any way so when revenge and shield slam are both available, there is a 50/50 chance that it will use one or the other, resulting in a DPS loss when revenge is selected.
Many macros also only prioritize revenge over devastate at the start of the sequence, which will result in further DPS loss when devastate and revenge become available at the same time and devastate is used.