iirc, that was a general thought about some members of Cagayan, too.
My guess is there are three main reasons for that.
1) From what I understand, they cast both this season and Worlds Apart before finalizing the theme, which leads to the other two reasons.
2) Some people were probably placed where they were in order to even out the tribes challengewise. If you swapped a few of the ill-fitting contestants out to more appropriate tribes, you'd probably wind up with a very stacked Brawn tribe and crippled Beauty and Brain tribes, depending on how the final rosters would look.
3) Several people fit multiple categories; as just a few examples, Anna could theoretically be on Brains, Nick, Caleb, and potentially even Joe could be on Brawn, Alecia and Liz could both be on Beauty. Conversely, a few (Tai, Alecia if you're not into the Barbie look) don't seem to evenly fit into any of them.
At this point Tai and Alecia are two of the most entertaining people in the cast, and that's ultimately why I don't mind that the theme's execution isn't perfect. If CBS prioritized theme, we wouldn't have them, we'd have two random mactors. Personally I'd much rather be entertained by having ill-fitting people there and have the theme suffer than have the theme work beautifully with a mostly subpar cast. (a la Cook Islands or Redemption Island. *shudder*)
That's just my two cents anyway.
