Preface: These are facts, not my opinion. Also, premading and wintrading are two extremely different things and I will use each word very carefully.
AB is a "better" BG than WSG in terms of mathematical honor per hour, but only if you can 4-5 cap every game. For the past few weeks, Horde and Alliance ranker groups have been wintrading. Both factions queue both battlegrounds, they match into each other guaranteed because of the new queue system, and then Horde wins an empty AB and Alliance wins an empty WSG.
For the past several weeks, there has been no Alliance premade that could really challenge this main horde group in AB, and this is why the Horde wintraders have controlled AB while Alliance wintraders fall back to WSG.
This week, Cerina/Patuljak/Yousayso premade has been fighting the "main" Horde group of Schalk/Jeromes/Tralala or whatever in AB, and the Alliance premade has been mostly winning. This is fucking awesome, big props to Patuljak and his team that are trying to shake things up. (And I have to give the Horde some credit for not dodging or being scummy, but it is AB bonus weekend, and I'm being told they are still getting a fair amount of empty games, inbetween games against Patuljak prem, so we'll see what they do next week

)
Now, here is what's going to happen next. Again this is not my opinion, it's fact. The Horde and Alliance premades might continue to fight for control of AB (the "better" BG in terms of honor/hour) even after the bonus weekend ends. The competition in AB might last a few more days, or even a couple more weeks, but eventually one side will give up and fall back to WSG, and when this happens the wintrading will resume.
When the same ~30 players fight each other for 14+ hours a day, it simply doesn't take a lot of days to figure out which side is the better team. And I know people love to use the word skill, but the truth is that the team with a better class composition, better gear, and more eng/consumables is going to win. (Obviously, if there is a drastic difference between the 2 teams in terms of communication or player skill, there are exceptions, but this is a pretty rare thing in Vanilla BG's IMO.)
Anyway, the point is that it's only a matter of time before one side realizes that they aren't going to get the standings they need if they keep losing (or even failing to 4-5 cap) AB, and they will fall back to WSG, leaving the other side free to farm empty AB all day.
So, while I am super excited to see a little bit of competition returning to BG's, the sad truth is that all that is really being competed over is the right for your faction to have empty AB's. And speaking of sad truths, wintrading has been going on unpunished for so long now that more and more people are doing it every day. I often solo queue during North American/Chinese play times, and there are usually multiple groups of low rank players farming empty games.
So yeah, it's great that some premades are fighting each other again, but how long can the current Horde group(s) afford to lose/3 cap AB? As soon as the bonus weekend ends, Horde will probably fall back to WSG. And even if they don't fall back right away, you can only ask people to lose to the same team(s) 16 hours a day for so many days before human nature will cause them to join WSG and accept the free wins. Can you really blame them?
TL;DR Glad to see some groups playing less like wintraders and more like premaders, but the fact is wintrading will never go away until Nostalrius either returns to the old system, disables multi-queue for groups, or disables group queue completely.