Man On First: Should I Steal?

Suppose you are a manager. It is the beginning of an inning (does not matter which one) and your first hitter gets on first base. The score is tied and it may be in the team’s best interest to try to swipe second base. Using Run Expectancy Matrices and Stolen Base/Caught Stealing Data from 1993-2010, courtesy of the Lahman Database, we can determine whether the runner should be sent.

Using the Lahman Database, it is easily determined that the average SB% is 69.9%, so we shall assume that the runner in question has a SB% of 69.9%, for the sake of argument. To determine whether it would be beneficial or not to steal, all that needs to be done is to calculate the expected payoff of a steal vs. the payoff if one does not steal. If the difference is positive, then one should steal, and vice-versa. The payoff of a steal can be represented as the following:

.699536 * SB + .300464 * CS, where SB and CS are the payoffs for a stolen base and a caught stealing, respectively. These payoffs can be put into a neat table, one row showing the probability of scoring one run when stealing, and the other column showing the average number of runs scored when stealing.

0 outs

1 out

2 outs

Prob. 1 run scores




Avg. # runs scored




This doesn’t mean anything when standing by itself, so this next chart will show the difference between stealing payoff vs. non-stealing payoff:

0 outs

1 out

2 outs

Prob. 1 run scores




Avg. # runs scored




So, what does this all mean? This would really only make sense given the context. This chart basically shows that stealing will increase the probability of scoring a single run in an inning, but will hurt the chance of a multi-run inning. If a manager is facing Clayton Kershaw, then it would be in their best interest to score a run in any way, especially if the possibility of scoring a run in the future is bleak. This can work similarly in the playoffs, where the run differentials are often smaller and opportunities for run scoring can dwindle quickly. But in a regular season match-up against an average to below-average team, it may be beneficial to shoot for multi-run innings to pad leads.

What this also shows is that baserunning, while important, is not the most crucial aspect of the game. Rickey Henderson, even during his prime, only generated approximately 3 WAR from his 100+ steals in a season. To illustrate this, let’s look at the chart of differences one more time, but instead I will use the SB% of Rickey Henderson–80.76%.

0 outs

1 out

2 outs

Prob. 1 run scores




Avg. # runs scored




This pretty much works in the same fashion as the previous table in that the probability of a single run scoring is obviously higher than that of the average number of runs scored in an inning. But this shows that with even one of the best base-stealers in the history, on average he could only increase the probability of one run scoring by ~10%. Now, that is pretty good. And because every box is positive, it would behoove a manager to send Henderson in most cases. But, if this is only for one of the best, how consequential of a strategy could base stealing really be? And in effect, it’s mostly inconsequential. It provides a possibly small advantage depending on the scenario. Given all of this: should the runner from first be sent? It may sound unsatisfying, but the answer is: it depends, and it may not make a difference.

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