I'm sure all baseball fans will be aware of the fact that on July 12th, the MLB All-Star Game is taking place. However, did you also know that this also marks the arrival of a three day window in which to unlock the Mid-Summer Classic achievement?http://www.trueachievements.com/a148048/midsummer-class....htm
You'll have a period of three days to obtain it, from today July 11th until July 13th, and will have to head the MLB Today section in game which should present you with the appropriate match-up.
It's assumed that the achievement unlocks upon completing the game, so see it through to the end to claim your prize. Good luck!