In addition to new stats, there are the abilities each tank will see affected by readiness to consider. There are also Draenor Perks for each tank spec, granted randomly as we level from 90 to 100. There are changes in what abilities exist, in what specs get them. Vengeance is gone, replaced with Resolve, buffing our self heals and absorbs. In short, while the basic idea remains the same - generate resources via attacks to spend on damage reduction in one fashion or another - how we go about it, how it interacts with us has so many changes that it's worth discussing in length. There's so much change coming in that I don't pretend I'll catch all of it, which is why we have comments, after all.
So what do I expect to see out of tanking coming 6.0? It should be noted, this discussion is based on the Warlords alpha patch notes and such datamining as I've looked over, and I freely admit I only tank on one class, so while these are general observations I may be missing key class specific factors.