Another factor to add to our discussion - noticeable set-ups which I HAVE noticed in the past but have remained silent on. Pinstrip brought up a good point in another thread:
What is it about this season that feels so wrong? Why are the challenges so lame and easy? I'm starting to believe that the producers of the show are slanting the show to benefit one team over the others and that team would be Maria and Tiffany, the poker players. We have an all female team and none of the challenges have been physically challenging so far, something that's been know to do in the women in past seasons. What city did the producers choose as the final destination, Las Vegas, the one city Maria and Tiffany will know like the back of their hand.
Last year felt much the same way with so much time spent in China which benefited the eventual winners.
I'm almost willing to bet this years race will not end in a foot race just to help push Maria and Tiffany across the finish line without the traditional last challenge.
This season certainly does seem to be geared toward physically weaker teams rather than strong ones. Look what happened to the strong teams in the last two seasons. I'm going to even propose that these set-ups may have been going on much earlier than now. Let's see:
Season 9:
This is the first season that looks like a potential (not very strong) set-up to me. Japan as the penultimate destination gave BJ & Tyler a huge advantage, assuming they could make it that far. I can't find evidence of any other favoritism in this season, though (thank goodness).
Season 10:
The finale seemed to be an obvious attempt in favor of Tyler & James. And I just barely got a new idea: with all the physically challenging tasks that season, could it be possible that the intended winners were in fact Tyler & James?
Season 11:
Honestly, this one shouldn't be here. The tasks were varied and didn't seem to favor any one team more than the others. Good thing, too, as it is the All-Stars race.
Season 12:
To me the "favored" team this season was Ronald & Christina, for much the same reason as Season 9. But again, other than that, no further evidence to me.
Season 13:
I can't see evidence in favor of any one team here, either. Feel free to argue if you have any.
Season 14:
I would have to say that this seasons team was (rather obviously) Tammy & Victor, with all the China this, China that, once again in the penultimate (and likely most critical) legs of the race. I can't think of more evidence at the moment, but I remember thinking that there was more than just this.
Season 15:
Pinstripe summed it up. There is only one female team, which to me seems rather odd. Likely because they don't want the "wrong" female team to win, so if a female team were to win, it would be the poker girls. There have been a lot of tasks and challenges that seem designed specifically for them. By far the most obvious promotion of any season.
Feel free to add to my list, 'cause I can't remember a lot right now.