Why Sacrifice?

In last night's game against the Baltimore Orioles Alexi Casilla came to the plate with Carlos Gomez on first and Delmon Young on second and no one out in the 6th inning. Casilla tried unsuccessfully to bunt the runners into scoring position. The Twins were fortunate he did not lay down the bunt because later in the at bat he laced a double off the baggy driving in Young and moving Gomez to third and kick starting a three run rally that tied the game at six. If Casilla had bunted the runners over it is possible the Twins don't win the game. Why does it make a difference? Using scoring expectation data from Baseball Prospectus' book Baseball Between the Numbers it becomes evident why.

• With a runner on first and no out a team has a 41.7% chance of scoring. Bunting him over changes that scoring expectation to 41%. No scoring advantage gain.



• With runners on first and second and no outs a team has a 61.6% chance of scoring. Bunting the runners over changes the scoring expectation to 67.4%. An increase of about 6%.
  

Those that argue against the sacrifice bunt say it is giving up outs. When Casilla came to the plate the Twins only had 12 outs left in the game. It can be said bunting in Casilla's situation was the smartest strategic move according to the numbers. The team would have gained nearly a 6% better chance of scoring, but with only 2 sacrifices all year and the way Casilla is swinging the bat is it a risk worth taking? Many Twins fans would say no.