In theory, Fox had a solid idea. Pair Joss Whedon’s new hour-long drama, “Dollhouse,” with “Terminator: The Sarah Connor Chronicles” to create a male-skewing sci-fi block on Friday night. They’ve had success on Friday’s in the past with sci-fi; “The X-Files” flourished there (or at least paid for itself) for several years. But The Live Feed reports that ratings for both shows were a disappointment.

The series premiere of Joss Whedon’s “Dollhouse” was seen by 4.7 million viewers Friday night and garnered a 2.0 preliminary adults 18-49 rating and 6 share. It was beaten in the 9 p.m. hour by ABC’s “Supernanny” (6.1 million viewers, 2.2/7) and is the lowest-rated scripted series premiere on a major broadcast network this season aside from NBC’s now-defunct “Crusoe.”

“Dollhouse” was paired with the midseason return of “Terminator: The Sarah Connor Chronicles” (3.7 million, 1.3/5), which was shifted from its previous Monday post. “Terminator” came in third place in the hour and hit a series low (by like 27%). “Terminator” beat NBC’s “Howie Do It” (3.9 million, 1.2/4), but not by much. Both “Ghost Whisperer” (10.3 million, 2.4/8) and “Wife Swap” (4.3 million, 1.5/5) did better.

I thought “Dollhouse” had a pretty solid premiere, but I was by no means blown away. The premise is interesting — that there’s a business that can reprogram “dolls” to become whatever its clients need. In the premiere, Echo (Eliza Dushku), started out as a party girl meant to entertain a rich playboy, but was reprogrammed to become an expert in kidnapping scenarios. Dushku looks great in a dress, but was a little stiff when she was trying to convince the father of a kidnapped girl that she was the right person for the job. I’m not sure that she’s the right one to carry the series, though future episodes will decide this. Stepping back a bit, I’m not sure how some viewers may react to seeing this pretty girl having her brain wiped at least once per episode. If the heroine doesn’t have some consistent character traits week-to-week, she may be tough to relate to.

I’ve liked “Terminator” all along, and I’m surprised that it is struggling in the ratings. I suppose this has to do with the collective attention span of fans of the movie series. Maybe stringing out a serialized plot over 20+ episodes is just too slow of a pace for those that fell in love with the action-packed “Terminator” films. This is a perfect example of a series that should have a 13-episode season, like many of the series on HBO, Showtime, FX and TNT. Shorter seasons means a compact season-long story arc and no filler, which is the main reason that a series loses viewership. When people get bored they naturally move on.

Another Friday show that is dying a slow death is “Friday Night Lights.” It consistently scored in the 4.0-5.0 range in its first season, and that fell to the 3.0-4.0 range in its second foray. Now, after premiering on DirecTV this fall, the show is garnering ratings in the 2.2-2.8 range as NBC runs the episodes for the non-DirecTV folks. Is this enough to keep this stellar show on the air for another season? Only the big-wigs at DirecTV and NBC know for sure, but given the state of the economy, it would be surprising if it were granted a fourth season.