Yeah he would have been the class of 13, but I think that they just refer to themselves that way regardless of actual graduation, since most of them finish their degrees via summer classes or whatever anyways.

2012 was the last year BC won a national championship so I think there's a (mostly for jokes) competition between the two classes because they obviously didn't win in '13. Regardless, he got lots of points for '13 this week and I kinda love that he felt the need to post that as a caption on a pic of himself with the cup.