No, I never saw those death matches. I have never read Rothfuss, to be honest and did not hear about him until Comatose brought up he was reading The Name of the Wind.
But I do understand what you are getting at and I agree with you, it is not fair to another author to get a character (who is difficult to write) exactly right. But that being said, you still don't want to see large discrepancies with characters in a continuing series from one book to another. It would be one thing if another writer tried to write that more difficult character in a short story (like in your example of the battles), but if you are continuing the 'main' series (like WoT), you want those characters to flow from book to book as much as possible. It really is a tough situation for Brandon, because as you said, Mat is more difficult to write.
What is good is from what I hear is Brandon has done a good job with the rest of the cast (do you agree?) and whatever discrepancies with Mat does not detract from the overall great job that Brandon did. As I said, by the time I get to TGS, I most likely will not remember the issues with Mat and maybe will not even notice it.