Tonight, Adam Dunn became the 23rd player in Major League history to hit a grand slam in the bottom of the 9th to win the game by one run. This feat has been dubbed an “Ultimate Grand Slam” and is only slightly more common than say, throwing a perfect game. The last player to hit one of these grand slams was Jason Giambi over 4 years ago on May 17th, 2002.
In terms of Win Probability, the Reds pretty much defied all odds to pull out a win for the ages. Dunn’s grand slam was worth about 90 points of Win Probability Added (WPA) giving his former season total of 30% a nice boost.
David Appelman is the creator of FanGraphs.