So everyone assumed the two sides re-upped just to plant the flag one last year on this console generation and move on, and given the lack of marketing communication I have seen about MLB 2K13, that would seem to be a correct appraisal. All of one (1) screenshot for the upcoming game exists, and from the description of the feature set it sounds like you'll be getting an updated roster, the Houston Astros in a new division, and little else. I'll also be very interested to see what soundtrack the game has, if it has any.
What 2K Sports says, or doesn't say, about this game in the runup to its March 5 release will speak to what we may expect from it. And here is, so far, the only hype video for the game. 2K did get the reigning American League Cy Young winner, David Price, but I doubt he cost very much. The game went to the Tampa Bay Rays for a cover star in 2010, coming off the stinging disappointment of MLB 2K9.
The other two players in this video are Giancarlo Stanton of the Miami Marlins and C.J. Wilson of the Los Angeles Angels. But it's strange that the video is hosted by Fox Sports' YouTube account and not 2K's.