The OP is a DK. Meaning that ZG, the level 60 raid, was easily soloable by a level 80 death in Wrath of the Lich King, when the Death Knight class was released. It was soloable by a lot of classes, and many people lamented that they could no longer get it when Zul'Gurub was removed.
To say it took effort other then to keep trying is laughable. It was luck-based, just like the Beta Invite.
It took effort by some classes.. at the time there was an achievement dedicated to it, several cloth wearers had to resort to bugging the encounter to kill it, because they couldn't survive the hits, and couldn't get a group they'd trust enough to not ninja it if it dropped. Now, we know that because of mounts becoming BoA in MoP, they could (and should) have rolled a DK to solo ZG, and have to wait for YEARS to be able to use it on their main.
It's luck, and effort, to get the ZG tiger (and other mounts similar to it). After I got mine, I helped as many people try to get it as I could before I got sick of running the place.