Like the title suggests, what are biggest drops (https://tvtropes.org/pmwiki/pmwiki.php/Main/SecondSeasonDownfall) from good seasons to bad seasons (https://tvtropes.org/pmwiki/pmwiki.php/Main/SeasonalRot) of a TV show? It could be any show that enjoyed some really good seasons and later (https://tvtropes.org/pmwiki/pmwiki.php/Main/LaterInstallmentWeirdness) some really bad (https://tvtropes.org/pmwiki/pmwiki.php/Main/DorkAge) seasons?

Like the title suggests, what are biggest drops (https://tvtropes.org/pmwiki/pmwiki.php/Main/SecondSeasonDownfall) from good seasons to bad seasons (https://tvtropes.org/pmwiki/pmwiki.php/Main/SeasonalRot) of a TV show? It could be any show that enjoyed some really good seasons and later (https://tvtropes.org/pmwiki/pmwiki.php/Main/LaterInstallmentWeirdness) some really bad (https://tvtropes.org/pmwiki/pmwiki.php/Main/DorkAge) seasons?

I'll give you one and it's not original but it's a great observation by the iconic George Burns, when the Tonight Show starring Johnny Carson went from 90 minutes to 60 minutes. That change ruined the show, there was something about that last 30 minutes a feeling that something interesting could happen here. From that point on the show seemed like a paint by the numbers exercise.

Roseanne's ninth season, Angel's fourth season, and Game of Thrones' eighth and final season all come to mind.

the 3rd to 8th season (or however long it lasted; I had stopped watching it by then) of HAPPY DAYS.

the 8th to 11th seasons of MASH

The second season of The Abbott and Costello Show. The first season was very funny and featured most of their routines. The second turned out to be a more pedestrian sitcom that wasn't as funny as the first.

Both Alice and Three's Company become crap after season 5. The Lucy Show after season 4 is awful. Mama's Family after season 2 isn't that bad but it's definitely not as good as the first two seasons. Night Court had a big drop in quality from seasons 7 to 9. The Facts of Life had an excellent season 8 but their last season was crap. Grace Under Fire saw a drop in quality in season 4 through its last season. Married With Children was crap after season 6. Sabrina The Teenage Witch became a dud after season 4. Reba kept repeating the drama between the two main couples in seasons 4 through 6. It wasn't as good like the first three seasons. Melissa & Joey was perfect before season 3 when they put them together. Then came a long lost daughter for Joey and it just wasn't the same.

Melrose Place is probably the biggest show that suffered a quality gap. Seasons 3 and 4 were the prime years of that show. Majority of the cast left in season 5. Season 6 had awful ratings to where FOX pulled it and aired the last half of season 6 with season 7 for the final year.

Shameless stopped being good after season 7. I think that should have been their final year. Season 8 was boring and season 9 undid everything they accomplished for a certain character. It didn't make much sense after that.

Forgot Charmed. The first three years with Shannen was a great show. Once she was fired, it became a rip off of fairytales and Harry Potter. They also focused too much on showing off the female leads bodies. It wasn't about the story anymore of three sisters fighting evil.

Law & Order SVU suffered after Christopher Meloni left in season 12. They added a character just like him making him Stabler 2.0 and it didn't work. Benson went from a strong detective to a victim for a lot of seasons. It isn't good after season 12.

Happy Days and Mash stand out the most. If you cut the last 4 years off both they would have been ideal.