GAON has finally released an article discussing the drop in DAs that many have noticed during the year. They mention both the ending of the grace period for old package prices and the new regulations against bulk streaming and buying in regards to digital chart manipulation (brought on by the concerns of several big name companies). This has led to changes in the 3rd quarter of 2013 in DAs and less so in downloads.
This chart shows the total DAs for the Top 100 songs monthly. GAON notes that the dip in February is less drastic than it seems because February has fewer days. There is a huge peak in April when Gentleman, the song with the highest DAs for the year by about 30 million DAs, was released. This was also when Genie was added to GAON's DA tabulations. From there on its has been a decrease with July DAs dipping below March. August was even lower, by far the lowest this year. The recovery in September was brought on by a crunch to release music and some big names releasing albums (G-Dragon, Busker Busker, Master's Sun OST) and the same is expected with October (Busker Busker cont. & IU) but still September was well below February.
This chart shows the average DAs for the Top 100 songs monthly from January to July compared to the DAs of the Top 100 during August and September. August sales were 51% the average of Jan-July while September was slightly better with 67% the total DAs of the average from Jan-July. GAON attributes the drop in August to the elimination of fraudulent bulk streaming and buying as per new government regulations.
Consistency has also been an issue as songs are remaining in the Top 50 for fewer weeks during the first quarter compared to songs released in the second quarter. #1 songs remained in the Top 50 for an average of 11.8 weeks during the first quarter compared to 9.8 weeks in the 2nd quarter. GAON speculates, however, that the changes made to streaming and downloading rules will mean an increase in consistency so that songs that are truly popular won't be pushed down by ghost accounts streaming and downloading a song thousands of times.
For more information and graphs see the source: http://gaonchart.co.kr/thema/view.php?id=90&gbn=opinion