User blog comment:SodaCat/Birthdates According to Graduation Year/@comment-2099017-20160124020917/@comment-5385060-20160125144450

Being held back does seem a possibility. Considering that Jimmy was expelled so often. Chances are he skipped class a lot, and got held back. There is also a possibility that he could be a freshman. Some kids are 15 at the start of their Freshman year. As Soda proved in her blog, pointing out when your character would have to be born to graduate at a certain year. Jimmy could have been born just out of the catchment area to be a freshman at 14, and started school a year later. Or he could have been held back a year in Kindergarten. That happens as well.