As part of "a big shakeup of CNN's troubled primetime lineup," the cable news network has cancelled Eliot Spitzer's In the Arena. Spitzer's show, which long struggled in the ratings, was originally a duet with conservative columnist Kathleen Parker. In February, CNN ditched Parker, and reformatted the show as a Spitzer solo act. But the program continued to flail, and Wednesday night's show was the last for the former crusading New York governor felled in 2008 by a prostitution scandal. Why did Spitzer have such a hard time finding a big audience, and what led CNN to give him the boot? Here, six theories:

1. 8 p.m. is cursed
"It's in a tough time slot, where Campbell Brown, Connie Chung and Paula Zahn all found rough going before him at CNN," says David Bauder in Forbes. It's no surprise that Spitzer had a hard time in this time slot, too, especially competing against Fox News' Bill O'Reilly, and MSNBC's Lawrence O'Donnell (and Keith Olbermann before him).

2. It's all about Anderson
CNN is moving Anderson Cooper 360 into Spitzer's old slot, making the network's "flagship program…. an even more important part of the channel's programming mix," says Brian Stelter in The New York Times. Cooper's show, which will also be rebroadcast in the 10 p.m. slot, is a "straightforward newscast" that "stands in contrast to the conservative-leaning 8 p.m. show on Fox News and the liberal-leaning one on MSNBC."

3. And maybe a little about Keith Olbermann
"CNN may also be facing new competition from former MSNBC host Keith Olbermann," says Marisa Guthrie in The Hollywood Reporter. Olbermann's new program on the niche cable network Current debuted last month, and it bested Spitzer in the target demographic (24- to 54-year-olds) multiple times.

4. CNN isn't Fox or MSNBC
Spitzer's show was CNN's "attempt to to bolster its primetime ratings by dipping its parched tongue into the restorative waters of ideological debate TV that has done so much for the ratings of rivals Fox News and MSNBC," says Lisa de Moraes in The Washington Post. But that's never been a winning formula for CNN.

5. The Time Warner brass never liked Spitzer
Spitzer was brought to CNN by former network boss Jonathan Klein, "who, against the advice of many, believed this broadcasting novice could carry his own show in CNN’s problematic 8 p.m. time slot," says Lloyd Grove at The Daily Beast. The disgraced former governor's new gig "irked several unnamed board members of CNN’s parent company, Time Warner, who never forgave Spitzer for his tenure as New York’s hard-charging state attorney general."

6. Spitzer was always a big risk
The show was "a risky move from the outset, given that just two years before, Spitzer was forced to resign as governor amidst a prostitution scandal," says Lucas Shaw at The Wrap. In its original iteration, Parker Spitzer, it never got the ratings CNN had hoped for. The reformatted version, In The Arena, got a "brief rating bump, but continued to struggle." Apparently, audiences still aren't ready to warm up to the disgraced Democrat.