I'm actually not all that surprised, since K was talking up how Seth was one of the best PG in the country pre-season last year and then had to try to find someone else to be the PG during the year as Seth proved to be an ineffective PG. Some part of that has to be leadership, and if Seth proved to K that he didn't have the leadership qualities K is looking for last year, why would he be named a captain for this year's team?
I really want to see Seth find his comfort zone and be a consistent and effective player, but apparently K sees that leadership is not something he has not been consistent or effective at. Perhaps this is a motivational ploy by K to try to provoke Seth into being more assertive and more of a leader, seeing as how K's tactic of praise last year didn't work.