ESPN recently announced that through its first 50 national NBA telecasts, viewership is up 7% compared to last season, averaging 1.72 million viewers per telecast. In a TV marketplace where viewer declines are the norm, those are good numbers.

But the numbers story that continues to pass under the radar is the sizable ratings increases being produced by several of the Comcast Regional Sports Networks, which includes not only CSN Bay Area, home network of the NBA-leading Golden State Warriors, but also CSN Chicago, CSN New England and CSN California.

Overall, out of the 15 times the Comcast RSNs went head-to-head with a national ESPN telecast prior to the Feb. 14 All-Star Game, CSN out-rated ESPN in those markets 14 times in total viewers, 12 times among adults 25-54 and 9 times among viewers 18-49, according to Nielsen data.

The ESPN Feb. 6 national telecast of the Golden State Warriors vs. Oklahoma City Thunder was the most-watched regular season, non-Christmas Day NBA game on the network since 2014, averaging 3.2 million viewers. Some 68,791 of those viewers watched the ESPN telecast in the San Francisco Bay area. Another 256,760 watched on CSN Bay Area, a 273% larger audience for the local regional sports network.

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In Boston, CSN New England has out-delivered the ESPN telecasts of the same game by 229% in households and by 231% among adults 25-54. In San Francisco, CSN Bay Area has out-delivered the ESPN telecast of Warrior games locally by 150% in households and by 101% among the 25-54 demo. In Chicago, CSN Chicago has out-delivered the ESPN telecast of Bulls games by 34% in households and by 31% in adults 25-54. And in Sacramento, CSN California has out-delivered ESPN's telecast of the Kings games by 11% in households.

Overall among the 15 head-to-head telecasts, CSN networks cumulatively have out-rated ESPN in their regional markets by 113% in households and by 79% in the 25-54 demo.

Ray Warren, chief revenue officer of NBC Sports Regional Networks, who oversees the Comcast Sports Networks, says a new group national advertisers this season have seen the value of the RSNs and have jumped in as regular advertisers across a bunch of them.

Among the national advertisers who have joined CSN's sports network telecasts this season are Cadillac, Michelin, Nike, Progressive, Exxon, Harman, Hyundai, New Amsterdam Vodka and Turbo Tax.

“The NBA RSNs are a story that has continued to get stronger as the season has gone on,” says Warren, whose CSN ad staff works in conjunction with the national Home Team Sports sales staff to sell advertising for the RSNs. “And as more brands look to target avid, live audiences, the RSNs will continue bring in a growing amount of ad dollars. There is a whole host of national TV buyers who understand that capturing the local fan’s viewership in a multi-market buy is a way to further expand reach.”

Adds Warren, “If you just make a national buy, you get lots of casual fans across the country, but the local fans from the markets the teams playing are from are the fans sitting on the couch from start to finish. They are not only watching the games but also the commercials.”

Warren cites the Jan. 25 game between the Warriors and the San Antonio Spurs that was pretty much a runaway win for the Spurs with the final score 120-90. The regional market household rating for the game was a 16.08, the highest-rated CBS Bay Area telecast ever. The game ended with the last minute posting a 15.2 household rating and 94.3% of the audience that began watching the game watched until the last minute.

It was the highest-rated Regional Sports Network delivered NBA, MLB or NHL game of any kind in a Top 20 market since September 2011, when a Red Sox game on NESN scored a 16.88 rating.

“Our audience in the Bay area was there till the end, despite the lopsided score,” Warren says. “It may cost a bit more to add market by market advertising to a national buy, but advertisers are reaching a more engaged audience and adding some significant audience growth.”