Bands that drastically changed musical styles

[MattSuspect]

For the hardcore kids, Cave In, the band was a metalcore stalwart of the 90s, just sick metal guitars and super harsh screaming, with the occasional offkey singing. In 2001 they released Jupiter, which was essentially a progrock album. Basically like a hardcore rush. The album was critically aclaimed they got signed to a major label, released a pretty mediocre follow up, then released another piece of trash after they were dropped and now are broken up.