1. New 80. A new level 80 tank is wearing or buys a new set of crafted Tempered Saronite armor or equivalent. He or she has lots of defense, but lacks in health (at least according to most PuG leaders) and is 15-25% away from the block cap. Total avoidance is relatively low. Whether this person is being geared up by a guild or working solo, he or she wants to run heroic instances for emblems and run dailies for cash, using that cash to buy iLvl 226 BoE epics (and a few iLvl 200 epics for slots like shield).
2. Average iLvl 227. The availability of higher-iLvl gear from instance-acquired emblems means that iLvl-213 / Naxx / T7 gear just isn't necessary when gearing up. With the exception of perhaps a shield or weapon, equivalent or better gear can be found via emblems or the auction house. Thus, a level two player with gear around average iLvl 227 actually has pieces that range from iLvl 200 (for shield and weapon) for 245 (for shoulders).
3. Progressing ICC Normal 25 / Normal 10 / Hard 10. A level three paladin starts with Ulduar-or-better gear (average iLvl 220-230) and is raiding with a guild that wants to progress through T9 and T10 normal mode content.
4. ICC Hard / End Game. The end-game progression raider is trying to maximize health.