1) Does an increase in Dodge decrease Rage generation to an appreciable amount?
2) At what value does more Dodge begin to decrease DPS due to loss of rage?
3) Does Dodge decrease threat due to loss of rage?
These are the mechanics of rage generation as per Wowwiki.
For Dealing Damage:
Main Hand Normal Hits: Factor=3.5
Main Hand Crits: Factor=5.0
Off Hand Normal Hits: Factor=1.75
Off Hand Crits: Factor=3.5
Rage Conversion Values: Rage Conversion at level 60: 230.6
Rage Conversion at level 70: 274.7
Rage Gained from dealing damage:
= ((Damage Dealt) / (Rage Conversion at Your Level) * 7.5 + (Weapon Speed * Factor))/2
For taking damage (both pre and post expansion):
= (Damage Taken) / (Rage Conversion at Your Level) * 2.5
Damage dealt has a much greater effect than damage taken in regard to rage generation for each point of damage given/taken. However, rage generated from multiple elite instance mobs banging on your bear at the same time will generate considerable if not the majority of your rage.
1) Increases in dodge will not markedly decrease rage generation until very high levels of dodge (probably greater than 50%).
2) In the PvE solo environment most rage is generated from damage dealt by the player, not damage done to the player by the mob.
3) The above are true, except when very large amounts of damage are being taken by the player (for example: Instance Bosses), then more rage is generated from damage taken than from damage dealt.
In conclusion, if you find yourself running out of rage, look for problems in this order:
1) Bear is not taking enough damage from enough mobs (bear doesn't have enough threat/aggro).
2) Bear's Dodge is too high.
3) Bear's DPS is too low.