You really do want a government to run a deficit in bad years.
Think about it. In bad years it is the safety net for a lot of people. And tax revenues are going to be down because it is a bad year. That means that you lose money.
However you also want to run a surplus in good years so that it isn't a problem to run a deficit from time to time. (Which is the half that politicians like to ignore.)
So in the long run you want government's budget to balance. But it is a really, really bad idea to make it balance every year.
Cheers,
Ben