Time Warner management is displeased with performance at some of the cable networks that are part of its large Turner cable-programming unit, the company’s chief executive said Wednesday in remarks that intensify the spotlight on recent executive churn at that operation.

“We are not satisfied with recent ratings and advertising performance at some of the Turner networks,” said Jeff Bewkes, Time Warner’s chairman and chief executive, during a conference call with investors. Bewkes specifically cited results at reality-series cabler TruTV and drama-centered TNT, noting that both networks would have programming on the air in weeks to come that the company hoped would meet with favorable audience reception.

At TruTV, Bewkes said, “we followed a couple of strong years with a significant drop-off in performance” that he expected to be corrected over time with new programs. At TNT, he said,  “over the past few years, we didn’t take enough creative risks with its programming, and as a result, TNT has lost ground with younger viewers.” Bewkes cited new series like “The Last Ship” set to debut in coming weeks that “should help TNT expand its audience.”

Still, he noted, “these types of changes take time, and we won’t get to where we need to be in the next quarter or two.”

During the call, Time Warner executives noted that Turner was experiencing “drag from the ratings” for its entertainment content.\

At issue, said Bewkes, was the success of a bevy of edgier, serialized dramas available on other basic-cable networks as well as subscription video on demand outlets that have found favor among younger viewers – and the advertisers who court them. He cited AMC’s “Breaking Bad” as an example. While TNT dramas like “The Closer” and “Rizzoli & Isles” were big hits among general audiences  – and designed to appeal to a slightly older viewer – Bewkes said sponsors are now placing emphasis on a new type of programming that tilts toward a younger consumer.

Bewkes’ comments come as Turner is without a chief programming executive for its entertainment networks. Steve Koonin, the longtime head of TNT, TBS, TruTV and TCM, left the company earlier this month to become chief executive of the Atlanta Hawks. A search is on for a replacement that could come from within the company or outside of it.

Small wonder, then, that when Koonin stepped down, Turner President David Levy noted that “Change is happening across our company now.,” in a memo. “In the rapidly evolving media business environment, it’s imperative that we embrace and lead change in order to drive growth across our businesses.” Levy will be supervising Koonin’s duties in the near term, including Turner’s presentation in the coming “upfront,” when U.S. TV networks try to sell the bulk of their ad time for the coming season. Another executive, Greg D’Alba, who supervised CNN ad sales for years, also recently left Turner.

Separately, Bewkes said the company expected a recent deal to stream a select catalog of older HBO programs on Amazon’s Prime streaming service would create additional interest in the premium TV service, as Amazon customers got a taste for HBO content. The company intends to invest revenue from the pact into new programming for HBO as well as new technology that helps distribute HBO content, such as the HBO Go service for mobile devices.