There was a time when Battlestar Galactica fans lived in constant fear of their favourite show being cancelled. It escaped unscathed but the BSG prequel show Caprica has not been so lucky – axed mid–run, with the final five episodes of the first season rescheduled to air early in 2011. According to Mark Stern, Syfy's executive vice president of original programming: "Despite its obvious quality, Caprica has not been able to build the audience necessary to justify a second season."

It has been a brutal year for cancellations in the US, with some shows killed when barely out of the gate – con-man show Lone Star, for example, was axed by Fox after only two episodes. Caprica fans should perhaps be grateful that they will get one full season, despite having to wait for the final episodes. But given that initial critical response to the Caprica series, which launched in January this year, was fairly positive it does beg the question: what went wrong?

Battlestar Galactica was considered a prestige show for Syfy, but BSG never enjoyed stellar viewing figures to match the critical praise. It was always likely that Caprica would face the same problem – but there were also further complications. As the US critic Alan Sepinwall put it: "Soap opera fans don't necessarily want to watch sci-fi … Sci-fi fans don't necessarily want to watch soap opera." Caprica, painted as a sci-fi version of Dallas, appears to have fallen victim of that: unable to keep on board BSG fans bitter at the twisted ending of that show, and unable to attract new blood. Some odd scheduling probably didn't help much either. The Caprica pilot was released as a standalone DVD in early 2009, but the actual series didn't get started until a year later, with only 10 episodes aired before another hiatus.

Or maybe Caprica was just never good enough – even for those who stuck with it. The show "seems to have spent most of its running time building up story blocks rather than telling them … There's real intelligence and ambition in Caprica, it was just hard work to watch at times," wrote Simon Brew of Den of Geek.

Syfy's next move seems to be to retreat to safer ground, having announced yet another BSG spin-off just ahead of Caprica's cancellation: a pilot for Battlestar Galactica: Blood & Chrome, which will explore the early adventures of a young William Adama as he joins the Colonial fleet as a rookie Viper pilot aboard Galactica, fighting in the first war against the robotic Cylons. This return to the grim combat setting of the Galactica looks like an attempt to win back many of the fans that shunned Caprica and its planet-side setting.

It's clear that Syfy are looking for another hit from the BSG universe, but there must surely come a point where the law of diminishing returns sets in? Over-spinning a franchise can hasten it's death – remember the Enterprise prequel show that ultimately heralded the death of Star Trek on TV? BSG has already seen its universe expand beyond the four seasons with two movies and a clutch of web-only mini-series. (In fact we have already seen a 'rookie pilot' Adama in the BSG Razor Flashbacks series of webisodes that aired online to promote the show's fourth season). Perhaps Caprica's demise suggests we've had one spin-off too many – and it's time to leave the BSG franchise in peace.