PC Gamer's Interview with a Hearthstone botter (It is 2 pages long)
The answer to the question in title is in page 2 of the article; you were most likely facing a bot. The most interesting part was the use of bot in arena matches. It still requires human intervention in the initial draft so the botters aren't using a program that auto selects base on the popular tier lists, etc. The article also stats that bots are popular in the region's night-time.
