While NBC is promoting its drama "The Blacklist" as a hit, some signals behind the show’s apparent ratings success aren’t clear, reports the Los Angeles Times’ Show Tracker.

The Monday night show, which stars James Spader as a con man helping the FBI solve crimes, was the top-rated new drama last week, and the top-rated drama overall among adults 18-49, the story notes.

"As for the negatives?" the story asks. With a lead-in from "The Voice," "Blacklist" held onto only 72% of the singing competition’s audience. That’s "lower than the 80% or so network execs would like to see. What’s unknown at this point is how ‘Blacklist’ would fare without one of the biggest shows on TV handing it a big audience," the piece says.

The story adds: "Also unclear? Whether ‘Blacklist’ has settled into a number it can deliver week after week. Monday’s show sank to an all-time-low rating of 2.9 in 18 to 49. The show premiered in September with a 3.8 rating. (One troubling sign: ‘Voice’s’ numbers were down too.)"

The report notes that NBC has already placed a full-season order for the show, which should give it time to grow artistically — and to build a solid audience.