Greetings.
One of the biggest issues I remember from the original Cataclysm run was that the Druid Feral Mastery for Bear tanks was pretty lackluster, thus hampering the performance of bears as MTs on raid environments.
While the masteries of the Warrior and Paladin tanking classes scaled with the increase of incoming damage (those were based on Block, thus percentual reductions to the amount of damage received from enemy hits given Cataclysm changes to that stat), and DKs had a pretty specific Mastery for their self healing, Druid Mastery instead reduced incoming hits by a comparatively small fixed amount, which made it viable on low damage hits, but immensely underpowered for the big hits dealt by most raid bosses (and the bigger the hits, even more so on harder difficulties bosses, the less useful Bear Mastery became).
This was clearly an issue, as feral tank mastery had to be completely changed and reworked from the ground up three additional times in the span of the next three expansions (while the other tanks Masteries, plus Monks Mastery later on, remain largely unchanged on their mechanics to this day, just tweaking numbers as needed for balance on major patches).
Maybe now with Cataclysm Classic it would be a nice idea tackle the Druid Bear Mastery issue right from the start instead, so it works more in line with the masteries of the other tanks, maybe by getting a somewhat adapted incarnation of the latest “Nature’s Guardian” Bear mastery.