1. Eric Matthews’ Intelligence
In early seasons, Eric Matthews was a goofy, wannabe weatherman who accidentally courted crazy girls with a penchant for songwriting. He was sort of stupid, but not completely idiotic. Then, slowly but surely throughout the seasons, he became dumber and dumber, until he was basically an adorable shell of a college kid, used as the fodder for everyone else’s jokes. Eric invariably impregnated the show with its comic relief, whenever it tried to make a buzzkill statement about underage drinking or premarital sex. But, how did he get so stupid? Even the Amy and Allen Matthews themselves are confused at how their first born turned into such a moron, but maybe he just left his brain at Chubby’s.
2. Stuart Minkus
The dorky know-it-all in the first two seasons showed back up in the graduation episode in Season 5, but where the hell was he the rest of the time? Taking classes at the fictionalized Pennbrook while the rest of the cast was still in 7th grade, listening to Feeny rhapsodize about ethics? Or maybe he was just filming his scenes for One Tree Hill, one of America’s other great shows about teens perpetually stuck in adolescence.
3. Jonathan Turner
Leather-jacket-cool-teacher went M.I.A. once the gang miraculously made it to high school. He must not have been running in the same crowd as Feeny, who could get a job as a teacher in whatever grade Cory Matthews happened to be in. Mr. JT showed up to save the day in 7th grade, when he would quixotically teach the lessons of respectably appropriate middle school novels like The Scarlet Letter. Once the lessons inevitably went directly over the group’s prepubescent heads, Jonathan Turner left to make out with that hot blonde teacher. And after Season 3, he never returned.
4. Cute Baby Sister Morgan
It’s every sitcom’s curse that didn’t have the Olsen Twins on payroll: what do we do when the younger sibling isn’t aging as fast as the rest of the cast? Cory went from 8th grade to 11th and Morgan is still 3. But we need her to be, like, fourteen. And soon! So, naturally, the show replaced cute baby Morgan with an annoying preteen Morgan whose mouth was perpetually open and running. Everyone hated her, and in case you’re wondering: the original Morgan is now pretty sexy.
5. The Counter-disappearance: The Omnipresent Mr. Feeny
Holy shit, this guy was everywhere. From first grade to senior year of college, George Feeny was standing in front of the classroom, fetchingly austere, spitting knowledge out to Cory, Topanga, and Sean (and whatever other bedraggled characters somehow managed to sit in their 12 person classroom.) He essentially lived in the Matthews’ backyard, popping his head in the door of their kitchen whenever something of urgency came up. Can you even imagine having your teacher interrupt your breakfast? It’s a teenage nightmare. And that’s exactly what Feeny was: a beautiful nightmare lurking alongside you through every single grade. And then, just when you’ve escaped, he follows you to college. He’s like the time you pissed yourself in elementary school — the damage done is inescapable.