With the release of phase 2 of The Burning Crusade Classic, Blizzard re-implemented same-faction battleground queues to fix the faction imbalance causing Horde players to wait for up to an hour to enter a battleground.
At the same time, Blizzard prevented pre-made groups of 5 or more players to queue together in order to make a fair playing experience but the development team also said they were searching for other solutions to re-enable pre-made groups.
Groups of this size will be matched with similar-sized groups and will fill the remainder of slots with random players if they do not queue as a full pre-made.
Pre-made Battleground Groups Make A Return In Classic TBC
Blizzard acknowledges that the system is not perfect and solo players may come up against an opposing pre-made team from time to time.
Given the system works as intended, this is a great change for the future of Classic WoW, giving players who wish to play as a pre-made the chance, while not ruining the Battleground experience for solo players queueing for fun.
It would be nice to know if these changes would ever see a change in future Classic servers such as the recently announced Season of Mastery, although it would have different implications as there is no arena and it would heavily affect the Rank 14 grinding experience.