Other examples you could have cited: WEEDS, FIREFLY
The counter-examples are compelling, though. THE WIRE’s season 4 is more consistent and more memorable than its S1. BUFFY was pretty mediocre for most of its first season. For most of S1, animators of THE SIMPSONS were still trying to figure out how to draw Homer, much like how JG (RIP) was still trying to figure out how do do Tony Soprano’s voice. And if MAD MEN had ended that early, we’d have never gotten to see what a badass Peggy became, which was the purest pleasure of that show.