Why? Have the Caldari suddenly found new vigor? Have the Gallente suffered a leadership crisis?
I'm going to speculate on why I think this is happening because what else are blogs for? I think it comes down to a small number of minor factors for the recent pendulum swings.
1) Evoke. The famous null sec alliance has joined the Caldari militia in January and the discipline and coordination of null sec fleets suddenly made itself felt against the more casual Gallente fleets. This bolstered the Caldari euro timezone considerably and gave the Gallente militia less flexibility to operate freely.
2) Meta Changes. With pilots just coming to grasp on what the revamped cruisers, destroyers, and frigates can do, there is a lot of uncertainty in the warzone about what works and what doesn't. This experimentation can lead to more volatility in military operations.
3) Psychology. Quite simply, its easier to log in and join the fight when your side is winning. Defending the gains is less exciting and with fewer people logging in and organizing fleets, the enemy can gain ground and momentum for their own side's enthusiasm.
4) Plexing is harder... thus easier. Come again? The plexing changes of Inferno 1.1 or whatever it was changed the plexes so that warp ins were right on the button (and fewer NPCs in the plexes) so that plex farming was a more dangerous occupation. This means that each side lost a lot of plex farmers only in the miltia for ISK. Thus pilots who are plexing for occupation control don't have to compete with the other side's plex farmers, thus making their plexing efforts count more in comparison. In a nutshell, plexing for conquering purposes is more effective and gains made in out of the way systems are not rolled back by the enemy farmers and thus don't have to be re-plexed. Thus plexing is easier and more effective, which when coupled with (3) leads to more momentum.
5) Burnout. A lot of Gallente FCs put in a lot of hours leading fleets to conquer the warzone and maintain momentum. Once accomplished, they took a deserved break allowing the angered Caldari militia to strike and gain ground.
6) Lack of ownership. This is a big one. Its hard to motivate people to defend systems once they move any of their assets out of the way. Yes, militia pilots can invest in the systems and get minor improvements to number of slots and such in the stations, but their is no rallying "protect the
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Do I think the pendulum will swing in favour of Gallente again? Do I think Caldari will continue on to conquer all the warzone in reprisal for the enemy's earlier success? Its hard to say at this point as there are a few big Gallente militia corps that would not like to see Nennamailia or Vlillier fall, but then I doubted Heydieles would ever fall and its gone now.
Time will tell. Until then, I'll see you Caldari scum in space. ;)