Many fans of The Flash found themselves asking the same question at the end of the show's third season: "What has happened to this show I used to love?"
It was a valid question. When it debuted in 2014, The Flash was a sensation. Though ostensibly a spinoff of Arrow, the show had little in common with that dark, gritty, street-level vigilante show. The Flash embraced the sense of wonder and elation at the heart of superhero stories. Being a superpowered crime-fighter wasn't presented as a grim burden, but as something exciting and morally righteous. Grant Gustin's Barry Allen was an endlessly charming lead, his affable, nerdy energy propelling the show forward at all times.
The supporting cast was loaded with ringers: Cisco Ramon (Carlos Valdes) became one of the few comic relief sidekicks who was genuinely funny and not grating; Caitlin Snow (Danielle Panabaker) was the genius, slightly awkward rock of the team; Jesse L. Martin's Joe West was television's surest bet to deliver a tear jerking moment on a weekly basis in the days before This Is Us. And perhaps most crucially of all, Tom Cavanagh's dual performance as both Harrison Wells and the evil Reverse Flash, Eobard Thawne, gave the show a deeply compelling villain that the audience was emotionally invested in. That first season is still a note perfect season of superhero television.
Things began to feel a little off in season 2. The show seemed to be repeating too many of its old tricks, with yet another big bad speedster who debuted as a stealth ally in Zoom, played with decidedly limited charisma by Teddy Sears. The show also began slouching into the sort of stock soap opera plotting that has plagued the worst eras of Arrow; characters would lie to each other for no discernible reason other than to drive plot developments, and Barry would descend into self-defeating angst.
The second season finale - which saw Barry disregard pretty much every lesson he'd learned about time travel and his own moral compass to go back in time and save his mother from Thawne - set up the show's nadir, season 3's "Flashpoint" arc. Barry's time-meddling created a vastly different reality, and when eventually Barry realized he has to reset the timeline, he found that not everything could be put back the way it was. Cisco's brother dies, Caitlin becomes saddled with the Killer Frost powers of her Earth-2 counterpart, and a melodramatic rift between Iris and Joe is concocted. It made for a gloomy, miserable start to the season, and it only got worse when the season introduced yet another speedster villain in Savitar - by the far the show's worst.
It turned out, under his thrift store Power Rangers armor, that Savitar was really a time remnant version of Barry: a scarred, bitter mirror of the show's hero, who was only slightly more miserable than the real Barry was at that point. The season ended with Barry seemingly sacrificing himself to stabilize the Speed Force, leaving his teary eyed friends and family behind. It felt like the show had maybe realized it had lurched too deeply into the darkness, and there was a genuine question whether or not the show could right itself going forward.
Season 4 answered that question almost immediately. Barry is expelled from the Speed Force and, after an episode of amnesia and aphasia, returns to the earnest, charming persona that so brightened the television landscape in its first season. The show took Barry's rebirth as an opportunity to essentially reset itself. It's embraced its strengths in ways it hasn't in many seasons, and discarded some of the tropes that have been holding it back.