Major League Baseball has signed eight-year extensions of its TV rights deals with Fox, TBS and the MLB Network, effective in 2014, that double the value of their previous pacts.

At more than $800 million combined annually, the Fox and TBS deals represent another revenue leap for sports in general and MLB in particular, as live events continue to become more and more prized in the fractured broadcast market.

The agreements follow MLB’s extension of its deal with ESPN in August through 2021, at an average annual rate of $700 million per year that also doubled their previous arrangement. MLB’s previous deals with Fox ($257 million per year) and TBS ($149 million) would have expired at the end of 2013.

The pacts include TV Everywhere rights that will allow the networks to simulcast games across platforms. Significantly, the Fox deal also spells out the rights to broadcast as many as 40 games on a nationally distributed Fox cable channel, amid speculation that Fox will rebrand Speed into a broader sports network.

“Throughout this deal, we have flexibility to some degree on distribution of the games,” Fox Sports Media Group co-prexy Randy Freer said on a conference call. “As many of you have read or heard, we continue to evaluate the potential of a national sports channel. … There will be a lot of things to come in the not-too-distant future.”

Through its new deal, Fox will double MLB’s Saturday regular-season telecast windows to 52 per season, while retaining exclusive rights to the World Series and All-Star Game. TBS will have rights to afternoon games on the final 13 Sundays of the regular season.

Fox will continue to split rights to baseball’s league championship series with TBS, alternating leagues each year. Baseball’s four division series will also be split between Fox and TBS, with MLB Network airing one game from each series.

Wild-card playoff games, newly instituted in 2012, will be divided between TBS and ESPN beginning in 2014.

Fox also contracted the ability to launch an MLB-branded nightly regular-season highlights program that would include live-game look-ins. Spanish-language network Fox Deportes will have parallel rights to air all Fox games.

In an interesting development for subscribers of MLB Extra Innings and MLB.TV, they will have the opportunity to watch some Saturday games that were previously blacked out because of Fox’s exclusive window. However, some geographic blackouts will still apply.

MLB Network, which launched in 2009 and now reaches 75 million homes, will air 150 regular-season games per year and also broadcast the MLB draft and the All-Star Game selection show, along with regularly scheduled studio-based programs such as “MLB Tonight” and “Quick Pitch.”

MLB’s continuous relationship with TBS parent Turner dates back to 1973, when the company began televising MLB games on WTCG (now TBS).

“This new agreement adds considerable value to our portfolio of offerings,” Turner Broadcasting prexy of sales, distribution and sports David Levy said. “We’re pleased to extend our relationship with the MLB brand across multiple screens to create an even richer baseball experience for our viewers, advertisers and distribution partners.”

American Cable Association prexy and CEO Matthew M. Polka decried the MLB deals and others like it for their effect on the consumers.

“Insane sports contracts are destroying a business model that once balanced the interests of consumers, pay-TV operators, programmers and advertisers,” Polka said in a statement. “If sports leagues, broadcasters, and programmers are unable to moderate themselves, then ACA will have no choice but to join with consumers to seek intervention in this increasingly broken marketplace.”