Reduce the queue time in arena and add preparation crystals
When you are too high on mmr you have to wait at least 2-3 min for arena with additional 1 minute in box (since there is no preparation crystals) - which is 30-40 min for 10 games spent just on waiting which is quite a lot. Reduce it to minimum when there is any other team in the queue - more teams at the end of the season will be high rated which will make pvp look more alive, and ppl will be playing WoW and not queue simulator.