The Bad Batch storyline, as it appears in Clone Wars, had initially been pitched for earlier in the series. It was brought back to fruition in Season 7. It was directly inspired by Star Wars creator George Lucas. He wanted the Bad Batch to have superior skills but not fall into the realm of superheroes. Clone Wars Season 7, Episodes 1 to 4 are all about the Bad Batch. This is where they're first introduced to us, and The Bad Batch series picks up not long after Clone Wars left off.