Yeah that was a long time ago, reason was that "Decimation" proccs was double dipping on the haste so you casted Soulfire's twise as fast, Demo warlocks was very strong engame too at this time.

300 MS is horrible, and I can tell you right away that's the reason you loose at least 1k dps if not even more, being Horde helps out too with the racials but not nearly enough as having good latency.

I have played with many American players in the past and we did a lot of tests to se what the difference is between 2 exactly same geared people and both was like, really pro with their class so there wasen't such big skill difference, and the DPS difference was staggering, Latency plays a huge roll in this game.
We used to have 2 retribution paladins, both really skilled long time players, both at bis gear, 1 with 30 MS and 1 with 250 MS, The dps difference was around 2K every single fight, this was at bis gear so they both had like 6,9k Gs.
The biggest difference was Healers, due to how fast the Tanks can take damage and how slow reaction the healers got from the huge MS made it very hard, They had to constantly spam heals to counter the reaction time, mana wasting, but atleast the raid survived.
Ah that's really great info you gave. It's actually crazy to think far good ping goes. With the decimation fixes, do you know how hybrid still performs compared to the other specs? At end game level and early level (naxx BIS)