Using the word "match" for 2nd years picking rotations is kinda odd.
Anyway, at PCOM you rank 12 different rotation orders and they do a lottery where you get your top pick, if there is space, otherwise they move down your rank until you match into an empty spot.
Then within our rotation groups, we do a points/draft system to pick rotation sites. We rank the sites within each core rotation and on draft day, we meet as a group and go through everyone's picks. This system actually works pretty well because majority of people in my group got their top 5 choices for almost all of their core rotations. I also know several people from other groups who reported the same results.
I'm pretty happy with the choices that PCOM offers as far as rotation sites go. Only critical thing I'd have to add is that they have lot of rural sites that are too far that I don't care to rotate through.
But like I said before, the draft system works pretty well that I didn't even come close to getting a rotation site that was considered "rural" by any stretch of imagination.