
Originally Posted by
Dowty
Outs are the currency of baseball, and they are extremely valuable. In a sacrifice situation, you concede one of those outs for baserunner position. Sure, the advance in baserunner position is great, but because you traded an out for it, the cost is greater than the gain in terms of run expectancy.
Of course a sac bunt is better than a GIDP, but you're comparing outcomes. Signs are called based on expectation. When you tell the hitter to swing away, you don't know going into it that the guy is going to GIDP, but you have to be willing to take that risk because the percentages tell you there's a better chance of an even more advantageous situation than what the sac bunt would provide.