The Business Journal:
According to industry data, the Pirates saw their average number of viewers dip about 15 percent in 2008, compared with the previous year. The Pirates averaged about 32,000 households watching each game, according to research compiled by the Sports Business Journal...
The Washington Nationals continued their four-season streak as the least-watched team in Major League Baseball Their viewership was down about 50 percent, the Sports Business Journal found...
During the regular baseball season, both national and most regional sports networks reported viewer declines.
That 15% figure sounds alarming, but FOX Sports had a 12.5% drop in its overall game viewership, so the Pirates were only a bit worse than all the other teams FSN covers. Still, the Pirates only beat three teams in average viewership: the Nationals and Orioles (who are both broadcast on the same flailing network) and Royals. Neither article linked here states reasons for the overall decline of viewership, but I wonder how much of it has to do with MLB.tv, which is generally what I watch. If I couldn't, I'd probably go to bars with satellite TV every so often, and I'd watch more Padres games on local broadcast.
In any case, it'd be interesting to see a month-by-month breakdown of the Pirates' viewership. The team didn't play that badly in the first half, and the attendance really seemed to be awful in the second half (although the official figures don't suggest there was much of a change).