Just how successful have Netflix's original shows been, really?

CBS chief research officer David Poltrack took a critical look at that question at the UBS Global Media Conference in New York on Monday.

Poltrack credited Netflix with striking original TV gold with "House of Cards" and "Orange is the New Black" in 2013.

"These are first rate programs, and they are critically important in bringing new subscribers to Netflix," Poltrack said.

However, he said, "it has been more than one year since Netflix introduced a true new hit program."

A jab at the fast-growing subscription service? Sounded like it. Poltrack's point was that while Netflix has become a "player in the original content business," the company isn't inherently superior at picking hits, compared to traditional TV.

Netflix's "batting average is below that of the pay cable networks as well as the broadcast networks," Poltrack said.

He added, "They do not appear to have found any magic formula for success in that game."

Poltrack didn't mention the fact that 2014, for Netflix, has been more about preparing future series than about introducing them to the public. The service did premiere an animated comedy, "BoJack Horseman," along with second seasons of "House," "Orange" and "Hemlock Grove."

But most of the shows that Netflix hopes will be hits haven't come online yet. These include "Marco Polo," which starts streaming at the end of this week; and "Bloodline," "Unbreakable Kimmy Schmidt," and "Daredevil," which will all premiere in 2015.

Netflix is also ramping up its production of original shows for children. It introduced "VeggieTales in the House" last month and has another one, "All Hail King Julien," coming up later this month.

At the same UBS conference on Monday, Netflix chief content officer Ted Sarandos predicted that his company would "eventually be the largest producer of original content in the world."

But it's taking time to get there.

Poltrack, during his presentation, shared research about Netflix viewing habits. According to the research, Netflix users watched an estimated 1.1 billion hours' worth of Netflix's five original series last year, while streaming repeats of the CBS hit show "NCIS" on its own accounted for 800 million hours of viewing.

Poltrack also said that Netflix's original shows added up to just 6.6% of the service's adult viewership -- assuming viewers watched each episode just once.

Much of the rest of the viewing is of network shows licensed by Netflix.

NBC's "The Blacklist" and ABC's "Once Upon A Time" led the way, according to Poltrack's research, accounting for 7% of Netflix's viewership.

Poltrack acknowledged the "frenemy" nature of Netflix for his and other networks: "Netflix is a formidable competitor, but they are a valued partner as well."