The Horde levels 50-60 guide has been rewritten and revamped.  My 1-60 Horde leveling guide is now completely updated for the 1.12 Drums of War patch.  As you can see it is about 15% larger than the 40-50 guide (single largest guide page yet).  There is also a lot of route changes.  I moved the entire Silithus section from level 55 to level 58, which allowed me to include a lot more quests for that zone.  There is also a lot of other improvement to the route, including adding a lot more quests into the guide, mostly from Moonglade, Silithus and Eastern Plaguelands.  This will make the final level 59 grind much shorter.
My general (unfounded) suspicion is that mob damage tables are mostly correct, but there is some sort of mitigation/damage reduction occurring that has yet to be explained. The only way the tiger could do regular damage to a higher armour Tips and 1-3 damage to joana is if there is some mitigation occurring for joana and not tips, or if they are on different shards/layers and for some reason the stats are different between the layers (extremely unlikely/impossible), or the tiger in the joana clip just happens to be born with a disability. But I should probably leave the baseless conjecture to the experts.
The argument for this is simple: what makes classic WoW great to one player might be different from what makes it great for another. And who are Blizzard's designers to say which old features were just good or bad design for each player? It's an approach that shows Blizzard believes (at least to some degree) that WoW doesn't just belong to its creators but to its fans. That struggle between authorial intent or game design orthodoxy and "the player is always right" is at the heart of many of gaming's big contemporary controversies. But so far, Blizzard seems committed to its plan with regard to WoW Classic.
HOWEVER, I did find out that there was an exploit to get around it (one of those rare exploits where you would WANT a bit of lag). Basically if you spammed “X” to sit/stand/sit/stand, then if a mob hit you while you were sitting and right as you were standing up, then it would register as a crit, but on the server side you would be standing, thus allowing the ability to proc.