Re: in-season and off-season
If you are referring to CrossFit Football's site, typically you do the DWOD and SWOD based on your sport's status. So if you are playing American football, you would do the in-season WOD's during the Fall when you are playing football. Once the season/football stops, you can go to the off season workouts.
So in-season will be when you are playing your primary sport. Off season will be when you are not playing sport.
If you play an intensive sport that is all year round, stick with the in season program. It is set up to balance the demands of a full time sport and a training program.