Now I could be WRONG about this so let me know if I am. But from my lived Arena Experiance and now trying to do Research on the subject...
PvP Guides for Arena that were made when all we had were Private Servers... before TBC came out... DID NOT survive contact with the enemy... and what actually happened was that Rogue/X Comps and Double DPS Comps basically dominated the meta.
You can see this in the Video Time-Lines going from Private Server Tier Lists of 2's Comps... to Phase 1 in TBC...
However... even in those Phase 1 TBC guides... they often say things like "Low Resilance" "Things Might Change... SHOULD CHANGE... when Resilance gets higher in later phases"...
Two issues...
1. I PLAYED in those "Later Phases" and on Henhouse servers... and the increased Resilance didn't change the meta in the slighest...
2. I can do MATH and Can tinker with a gear-planner... and I have NO IDEA how going from 7% Resilance to 10-11% Resilance from Phase 1 to Phase 4+ is supose to change the outcome.
That's a 7.5% increase in effective HP if our enemy had 100% Cirt chance... to like 11-12% in something like +20 Item Levels...
Now I could be a big dummy... but I am pretty sure that in +20 item levels our enemies get more then +5% DPS increase. At least I would hope they do...
You could argue ARMOR is what changes the balance... but that only really works for Plate warers (so Druid, Paladin, Shaman, War) maybe a bit for mail... like the +Armor value on the gear can outscale DPS of enemies with Resil on top?
Could argue that a LOT of damage from X class is granded from the TRAINER so the game is at its most BURSTY in Phase 1 compared to later phases...
But at the end of the day I lived through it and correct me if you think I am wrong but... Rogue/X and Double/DPS... Dominates Arena was my lived conclusion.