In a last-minute trade that leaves Microsoft without its lead-off pitcher, Major League Baseball announced this morning it has signed a two-year deal with Adobe that will mean its online video app moves back to Flash.

It was Bill Gates himself who, in the spring of 2007, demonstrated Major League Baseball's use of Silverlight as an example of its worthiness to go toe-to-toe against Adobe Flash, and become at least equally as ubiquitous among online video platforms. But now, Microsoft is about to lose one of its most prominent partners in the race for equal status, as MLB's Advanced Media division (MLBAM) announced it has signed a two-year deal with Adobe.

Since MLB.com's relaunch in April 2003, at opening day of that year's baseball season -- back when it first used Flash -- according to this morning's statement, "fans have accessed more than 1.8 billion streams of live and on-demand multimedia offerings on MLB.com, representing nearly 200 million hours of participation. By the end of 2008, MLB.com will once again stream nearly 12,000 live video events, including Major League Baseball games and thousands of events for its various business partners."

The statement goes on to say that MLBAM had actually been working to develop new versions of its online video delivery system throughout this entire baseball season, suggesting that even though MLB.com was running Silverlight during that period, it had been preparing for the possibility of moving to Adobe's AIR platform.

The reasons why may have less to do with technology and more with the said ubiquity of Flash. The first public signs of a possible crack in the dam between MLB and Microsoft came last June, when during Apple's WWDC in San Francisco, CEO Steve Jobs demonstrated a new mobile app called MLB At Bat. The app enables the streaming display of replay clips, along with a score crawler, on iPhones. (It was at that time when many of us began wondering, since that's obviously not Silverlight, then if it's not Flash, what is it?)

MLB.com's mission in life, going back to its founding in 2001, has been to extend the power of baseball's brand from the game itself to the video delivery platform. But since that time, leagues have learned that the brand that already exists on that video delivery platform does not go away gently into that good night. So fast-forward to last August, when MLB signed a content distribution deal with ESPN.

That deal, which runs through 2013, gives ESPN.com exclusive rights to stream content from major league games -- an extremely lucrative deal. And in the small print toward the bottom of the two entities' joint press release that month, you'll find the following bullet point: "ESPN will work with MLBAM to develop interactive TV applications around baseball games and content."

That's when anyone who reads walls for the proverbial handwriting should have noticed that Silverlight's time on the field may become indefinitely postponed. ESPN does not officially use Silverlight. UPDATE: ESPN360.com, however, has historically used the Move Media Player, whose manufacturer announced last March will be making the move to Silverlight.

The handwriting may have been underscored just yesterday, when ESPN let the press know it's close to edging out Fox Sports for a deal to broadcast -- ironically -- the college football Bowl Championship Series through 2014. That deal would undoubtedly also include streaming video, which would further extend the reach of ESPN's platform, particularly in the mobile space. Again, no Silverlight.

While Silverlight 2.0 made some inroads with NBC last summer as the exclusive streaming platform for US Olympics coverage, there are indications that even that promotional bonanza may have backfired slightly. Some users may have been put off by the appearance of Microsoft's exclusivity in this arrangement. A recent non-scientific poll by Mashable.com shows more than half of survey respondents felt that the use of Silverlight in Olympics coverage actually put them off to the technology, for unspecified reasons.

In a forum of people commenting about this Mashable poll, one blog leader said he may have been persuaded to install Silverlight if someone really big had gone along with it. "The only thing that could get me to install Silverlight is if ESPN or NFL.com used it exclusively," wrote the proprietor of Polygeek. "But you're right, MS had the opportunity to hit a homerun with this."

This morning's joint statement from MLBAM and Adobe omits the word "exclusive," so it's conceivable that MLB.com could still use Silverlight perhaps as a fallback or alternative platform...though for the long term, that's doubtful. BetaNews has sought clarification from Adobe, and we'll bring that to you once it arrives.

Yesterday afternoon, Microsoft's Scott Guthrie posted an out-of-sync reminder of the various inroads Silverlight has already made, particularly among sports leagues and services: "Over the last month we've seen several major new deployments of Silverlight for media scenarios. For example: CBS College Sports is now using Silverlight to stream NCAA events from its 170 partner colleges and university. Blockbuster is replacing Flash with Silverlight for its MovieLink application. And Netflix two weeks ago rolled out its new Instant Watch service using Silverlight."

Guthrie, perhaps too obviously now, made no mention of Major League Baseball.

1:00 pm EST November 18, 2008 - A spokesperson for Adobe told BetaNews this afternoon that its arrangement with Major League Baseball will not necessarily be exclusive; in other words, it will not preclude MLBAM from using Silverlight in some applications.

"The correct terminology would be 'primary choice,'" the spokesperson told us, adding that the agreement "pertains to any MLB property that delivers live video."