So as stated in my original post, my tier list ranks each specialization from 1 to 31, and then divides them into 5 categories. In other words, the criteria to meet a tier list was defined as being in a certain quintile of ranking.
To have an uneven distribution of specializations through a tier list would imply that there is some sort of criteria that you are applying to each tier list (I.E., Tier 1 must have the best survivability, damage, burst, and control, etc etc). I do not wish to make any such implications. The only metric for this list is to be in the corresponding Tier for each Quintile. Tier 1 = 80-100%, Tier 2 = 60-80%, Tier 3 = 40-60%, Tier 4 = 20-40%, Tier 5 = 0-20%.
I think dividing the specializations evenly is the best way to approach making a tier list.
To address some specific examples that people have brought up:
Balance is a must have in a 10v10, but it's much more lackluster in Arenas. As I stated, this list combines all aspects of competitive level 20 PvP, as I did not want to make a list specific to BG's or Arenas. The potential use of my tier list could be to pick a class that is the most consistent throughout all forms of 20 PvP, rather than just in BGs or just in Arenas.
Restoration Druids and Guardian Druids, I would argue, deserve to be in the same tier. They bring very little outside of their capability for a large bite. While Restoration Druids are capable of FCing without the increased damage from being a tank, they don't bring much to the team in terms of healing or consistent DPS. Guardian Druids on the other hand are capable of some very impressive damage in Arenas, where they do not receive extra damage from being a tank. However, neither of these specs are consistently seen in competitive levels of play in Arenas, and only Restoration Druids are played consistently in Battlegrounds; albeit not for their own merit but because Guardian cannot be played. Restoration Druid stands on the cusp of Tier 2, while Guardian is just past the doorstep of Tier 4. I think that is a fair approximation of their overall merits at level 20 PvP.
Frost Mage and Feral Druids are both Tier 1, although for very different reasons. One other thing to keep in mind with an evenly spread Tier List is that the only distinctions being made are X Tier is better than Y Tier, and within each Tier the list of specializations imply an ordered hierarchy as well. Never do I make any assertion regarding HOW MUCH better one specialization is than another. One can assume that the difference between any two ordered specializations in this list is not necessary uniform across the entire ladder. In this instance, the gap between Feral Druids and literally anything else is ridiculously massive. Arms is the closest in terms of overall power to Feral, but certainly there is still a massive gap. Frost Mage is tier 1 because it is essentially a must-have in both Arenas and competitive Battlegrounds. The class is borderline oppressive in both of those environments; in battlegrounds, where Frost Mages have single handedly carried games before, and in Arenas, where it has been hypothesized that no team without a Frost Mage will win a 3's tournament.
I hope this clears things up. I would advise those of you who were surprised by my tier list to read the explanations that went along with the list so as to understand where I was coming from when I wrote the list. I think pretty much all of the questions that were posed to me in this thread could have been answered through simple reading.