They did the same with Family Guy and American Dad in their spring debuts, only airing a small number of the initial ordered episodes. I believe that the Cleveland Show would have only aired a handful of eps if it'd been aired on time, too.
I thought the show was improving, but now we'll never know unless AS picks the show up. Hopefully 'Sit Down, Shut Up' failing will encourage Fox to cancel their plans to revive The Pitts in animated form.