You're missing a step for it to be evolution and natural selection. The increased use of superior specs would have to further propagate those specs. Not just because they're better, but because there are more of them because they are better. Get it? And until everyone is checking those sites to determine what spec to use, that's not happening here.

Right, Firestride.

Also, there are no outside environmental factors that are constantly changing to influence the propagation of said specs. More importantly, there are not several groups of a given species (race/class?) that live in different places that have different environments, ultimately producing variation between the groups.

Yes, but if we're talking memetically propogated specs as our 'genes' we have to allow for the fact that these genes transfer through more than spec sites - there are those who respec based on what their friends tell them, those who respec based on something they heard in guild, those who do so based on analysing their own game, who might go on to share in these already listed ways.

So, Blizz creates (and modifies) the environment in which specs can enjoy success or otherwise. Success in propagation is determined by (1) the ability of the "sending" player to reach an audience (one on one, one to many), (2) the ability of individual receiving players to find (through developing friendships/finding sites/independently theorycrafting) and apply new specs, and (3) the actual and perceived benefit of any individual spec (eg EJ as our most reliable (?) source could put out a superb spec and a large swathe of the population would still have it post-nerf because they got it 3rd hand and are continuing to circulate it even though it's not that great a spec. Phew!)

All this being said - the notion of "levelling = evolution" is pure bs. Evolution created, and then got rid of the dinosaurs. If intelligence (our current benchmark for power) turns out down the track to be non-survival away it will go and glowing cockroaches will have their turn at the top of the pile. There's no tree with bigger/stronger is better at the top, just niches and accompanying strategies.