A new PvP season has started in the World of Warcraft, it came with the recent 5.4 patch. In season 14 you no longer have to play with a premade arena team in PvP. You can join on your own and be put into a group, you still have the option to queue with a team of 2,3 or 5. You will be matched against opponents based on the average individual rank of your team.
For the most part, the mechanics of Arena will remain the same. You’ll still gain and lose personal rating based on your wins and losses, though your Conquest Point cap will now be based on your Personal Rating. The rating requirements to purchase items will also be based on your Personal Rating. Likewise, at the end of an Arena season, the top players will still earn titles and mounts.
Overall I think the changes are positive and makes for a much more competitive playing field. You can choose to wait for your team mates, or you can dive right in.