Don't really know if it is intended to be a secret for as long as possible. I'm more apt to think it's closer to or all about laziness.
In 2012, apparently there was a message from Yahoo, in a couple of spots in early Feb, but not posted at or around this message board where it would make a lot of sense to see it.
Here is part of my rant that I posted last February .... There was a message from Yahoo that said Tues Feb 9 2012 for the start of league registration, then it was changed to Thurs Feb 9 2012. Saw a message that said the 'entire season' would start April 4, then whoops, that was changed to March 28. (perhaps after the realization that the A's/Mariners games in Japan were actually a part of the reg season schedule for those clubs)
You might find one message in a certain area, and another message with different info in another area. A very simple solution to the yearly guessing game would be for the powers that be at Yahoo to post a message at the top of the baseball message board section and then keep that message the same as any other messages anywhere else within Yahoo. If Yahoo really cared about what 'the unwashed masses' really wanted and cared about, then posting correct messages in proper places wouldn't be a problem.