In 2009 and 2011 WOW still had a SUBSCRIPTIONS competition...
In late 2011... WOW was expected to loose between 3 to 4 million subscribers due to the upcoming competition of the next big things.
These turned into free to play stuff in mid to late 2012 with the end result of having less competitive subs based games than expected.
It is a market mechanism of expectancy. People forget that WOW had the biggest challenges yet in late 2011.
2013 sees less pressure by lack of subscription based players on the same market.
At the same time --- in 2012 --- free to play games and IPad thingies did not make the huge impact it was expected to make. As free to play games on the internet = NOT equal to steady income revenue (see the crash on Zynga and Facebook, both UNDERPERFORMED in revenue DESPITE huge "user"/"player" numbers).
It is only logical that WOW subs no longer have this negative influence as P2P apparently proves to be more reliable than F2P.