For months and perhaps longer the issue and to me the biggest reason why people dodge in every pvp content is due to the immense unbalance of the match making. You face people where you have 0% chance to win which makes dodging a logical and understandable choice or you meet people where unless your group disconnects, you have 0% risk of losing. The game when it comes to group pvp is very influenced by group setup, gear level, connection and perhaps the least often mentioned, experience and with that synchonicity in the group from having been playing for a long time together. What that means and brings to the game is that you have groups or alliances that can only lose against each other whereas any other matchup is a 100% win. Solving this would have 2 major benefits. 1. more people can actually do pvp and 2. less dodging will occur.
My suggestion is to make the ranking and the mmr system that goes along it stronger or in easier words making sure that the more points you get – i.e wins – the matchups will increasingly bring harder opponents.