I'd say it's obviously Sanderson's work (you can tell by the average sentence length), but from the looks of it he's improved his Mat a bit. Not a huge sample size, but enough that I feel slightly more confident. The Mat chapters in the last two books have been the most dissonant from the rest of the series, which is no surprise--Mat's humor is so incredibly unique that nobody but RJ himself can really replicate it well.

I foresee Jame as a new temporary Juilin Sandar--helping Mat along the way out of an odd loyalty, but perhaps under the guise of money.