The actor - who plays Jack Donaghy - told Rolling Stone that the NBC comedy's 2010-11 run was a "low point" for the series.
"Season five ends, and I'm saying, 'Next year, I'm done' - then I come back, and season six is really good, we all had fun again," Baldwin explained.
He added: "Even anaemic 30 Rock writing is still better than everybody else's writing."
30 Rock will conclude later this month in the US following a final 13-part run.
Baldwin recently admitted that he had wanted to star in an eighth season, even offering to take a pay cut to help finance more episodes.
In the UK, the sixth season of 30 Rock will resume on Comedy Central on Wednesday, January 30 at 10.30pm.
> 30 Rock cast finish filming after seven seasons - picture
Watch a clip from 30 Rock below: