This kind of thing is only “quite unexpected” if you’ve been keeping your head where the sun doesn’t shine, but:
“Toy” is the top digital song by a male group in Korea for the first six months of 2016.
The Blooming Period album sold the most digital songs of any a male group in Korea for the first six months of 2016.
…but they aren’t really popular.
I’m kidding. Whoo! Yeah for Block B!
To put stuff in perspective and avoid annoying triumphalism here, though, I’m going to point out that BTOB, which came in sixth on the Korean male-group digital sales front, handily whips Block B’s ass on Oricon. So, you know, don’t get too focused on the horse race.