When to Attempt to Steal a Base

We can use the Markov Chain method to determine the potential benefit of attempting to steal a base.

Using the probablity of winning is one way to do this. We need to consider the probability of winning the game before the steal attempt. Then consider the probability of winning after a successful stolen base and the probability of winning if the player is caught stealing.

It is then a straightforward calculation to determine what the break-even probability needs to be to make it worthwhile to attempt to steal the base.

If the coach thinks the probability of the player successfully stealing the base is higher than the break-even probability, he should signal the player to attempt to steal the base. If the coach thinks the probability of the player successfully stealing the base is less than the break-even probability, then the coach should tell the player not to attempt to steal the base.

For example, consider the following situation. The score is tied in the bottom of the seventh inning and the home team has a runner on first base with two out. The probability of the home team winning the game at this point is calculated to be 56%.

If the player steals second base successfully, the home team would have a runner on second with two out. The probability of winning the game, in this case, is 60%.

If the player is caught stealing, the home team would be out of the inning and the game would go into extra innings. The probability of winning the game at this point would be 50% with two evenly matched teams.

The break-even probability would be 59%.

If the coach thought the player could steal the base successfully with more than a 59% chance, he should go ahead and signal for the player to attempt to steal the base.

Using the probability of winning values for all the possible situations in the game, we can calculate the break-even probability of attempting to steal a base.

Although I am using the Markov Chain results for two evenly matched teams, this approach allows for consideration of the speed of the particular baserunner and the arm of the actual opposing catcher.