Decay for honor is still in the game, despite blizzard saying it was removed in an official blue post.
Blue post:
This last week, I stopped 30k short of hitting my soft cap for next rank. I would have gotten rank 5 if I had continued obtaining the remaining 30k. However, I decided I was tired for the week. Knowing decay had been completely removed, I decided I would pick back up this week where I left off. This week however, all my rank 4 progress has gone back to zero