A lot of that had to do with SyFy dropping Doctor Who in the US after season 4 and BBC America picking it up starting with The Next Doctor. I'm not completely familiar with the issue, but I get the impression BBC America did a better job with Doctor Why than SyFy ever did.
Ah, yes, the sordid tale of
Doctor Who and SyFy.
The United States got
Doctor Who long after everyone else had aired the Christopher Eccleston series. And that was sort of the BBC's doing.
BBC Worldwide had a difficult time selling
DW to an American network in 2004 and 2005. One problem was BBC Worldwide's asking price -- they wanted, I'm told, fifteen million for the thirteen episodes. The other problem was, in the words of one of the networks who passed,
Doctor Who "looked cheap." The RTD era (until the specials) was shot in SD, there were frame rate conversion issues from PAL to NTSC that sped things up, and compared to other programs,
Doctor Who of that time didn't look good. (Even today, I'd say that the visuals of RTD era haven't aged well.) Faced with a high price tag for a product of uncertain interest that looked tacky (I'm not talking about the content, just the visuals), a number of networks (including Bravo and A&E) passed. (I've heard rumors that HBO also passed, but I have never, ever been able to confirm that it was ever offered to them.)
What forced BBC Worldwide's hand was the Region 1 DVD release of the first series in Canada. Worldwide made a deal with SyFy (at roughly 10 percent of what they had originally asked) just to get it on the air somewhere.
BBC America was never an option at the time. While BBC America's reach is okay today, ti was, in 2005, a very, very niche channel with a small viewer base.
SyFy didn't really care about
Doctor Who. It was hugely profitable for them -- compared to what they were paying for
Battlestar,
Doctor Who was a pittance -- but they also didn't really promote it. And
Who wasn't popular with a segment of
Battlestar fandom; they felt it was a poor lead-in to their show, both tonally and visually, and they blamed
Who for
Battlestar's declining ratings. (I even know a few who blame
Who for the cancellation.) SyFy dropped the series, largely because they went through one of their periodic periods of, "We don't care about science-fiction. That's not the audience we cater to."
When BBC America took over broadcasting the series, they developed an actual marketing plan. They knew the audience they wanted to target -- college-age and young adults -- and they invested a lot of money into promoting the series, especially at SDCC. (One of the issues they had with the split season 6 was that BBC America's marketing budget wasn't enough to cover two launches, spring and fall.) And they pay some production costs.