Cablevision is witnessing one of the most dramatic and rapid management turnovers we have ever witnessed in our coverage of the media universe,” says BTIG analyst Rich Greenfield — Wall Street’s fiercest critic of the company and its strong-willed CEO Jim Dolan. Greenfield commented after the Long Island-based cable operator announced that David Klein is leaving as head of Cablevision Media Sales, to be replaced by Gregory McCastle, who was with AT&T. The move follows the exit of COO Tom Rutledge (now CEO of Charter), CFO Mike Huseby (who just became CFO of Barnes & Noble), President of Cable Operations John Bickham, CMO Jon Hargis, Corporate Engineering EVP Jim Blackley, and Consumer Operations EVP Kip Mayo. Greenflield says that Dolan is taking control of operations because he blames the old guard for allowing the company to lose “both its technology and marketing edge.” The problem? “We simply do not have enough confidence in Jim Dolan to drive free cash flow  growth in 2013 and beyond,” Greenfield says. Cablevision has lost 58.1% of its market value over the last 12 months.

Here’s today’s announcement.

BETHPAGE, N.Y., March 20, 2012 – Cablevision Systems Corporation (NYSE: CVC) today announced that Gregory McCastle will be joining the company as president, Cablevision Media Sales, effective immediately. The company also announced that David Kline, who most recently led Cablevision Media Sales, is stepping down to pursue other opportunities.

Mr. McCastle comes to Cablevision from AT&T where he served as senior vice president, AT&T Services Inc. and was a member of the senior leadership team of the AT&T Advertising Solutions organization. In his new role at Cablevision, Mr. McCastle will lead the company’s advertising sales teams for Cablevision’s local cable and advanced platform services, its local media properties including News 12 Networks and Newsday Media Group, and the New York Interconnect. He will be responsible for developing the company’s sales strategy as well as advanced multiplatform advertising solutions for national, regional and local advertisers, and will report to Tad Smith, president of Cablevision’s Local Media group.

“Greg brings to Cablevision a disciplined approach to inventory management and a deep understanding of how data analytics and advanced advertising can maximize available media opportunities for clients across all platforms,” Mr. Smith said. “He is a veteran of the telecommunications industry, who has pioneered the development of targeted digital advertising and we are very enthusiastic to have Greg join our team.”

“Under David’s leadership over the past 15 years, Cablevision Media Sales has delivered industry-leading advertising growth,” Mr. Smith continued. “In addition, he has been a pioneer in the evolving advertising landscape, creating products that provide advertisers with enhanced relevance and greater consumer engagement. He played a critical role in establishing Cablevision as an innovator of advanced advertising solutions, including addressable and interactive television advertising as well as dedicated brand-specific channels. We thank David for his leadership and the contributions he has made to Cablevision over the years, and know that he will succeed in his future endeavors.”