Season 1 of One Punch Man has some of the most celebrated action animation ever. Season 2 looks like a different, much cheaper show. Same source material, same popularity — what happened?
The short answer: the studio and staff changed, and in anime, staff is everything.
Season 1 was made at Madhouse under director Shingo Natsume, who leveraged his personal network to assemble an all-star freelance roster — many of Japan's best action animators contributed cuts basically for the love of the project. That lineup was lightning in a bottle, not a repeatable process.
For season 2, production moved to J.C.Staff with a different director and a much thinner schedule. The new team couldn't attract the same freelancer firepower (top animators follow directors and friends, not titles), and it shows: stiffer layouts, less in-between animation, more stills and pans.
The underlying lesson about the industry: 'Studio X made it' matters far less than which specific people were free that year. It's why fans track directors and animation producers the way sports fans track coaching staff. Season 3's production has been under the same skeptical microscope for exactly this reason.
Quick structural answer since the existing one already covers the vibe:
For what it's worth — read the manga (Murata's redraw, not the original webcomic) if the animation gap bothers you. The art was always more the point of this story than the anime fully captured, S1 included.
