SoSH Glossary: Left on Base Percentage

Baseball is filled with statistics, rules, and archaic terms that can often form what sounds like a foreign language.The Sons of Sam Horn glossary provides a better understanding of these terms through straightforward definitions, clear explanations, and examples pulled straight from the baseball world. If there is anything you would like us to add to our glossary, please contact us.

Left on base percentage (LOB%), sometimes referred to as “strand rate,” is the percentage of runners that reach base but fail to score. LOB% does not use the left on base information provided in box scores, but instead uses the following formula:

Most pitchers will end a regular season with a strand rate near the league average, which has recently been around 72% or 73%. Pitchers with LOB% that deviate from league average will normally see their strand rate regress to the mean. Note – this does not mean that if the league average is 73% and a pitcher has a strand rate of 80% that you should expect his LOB% to fall to 66% going forward. Instead, you should expect it to be league average going forward, that is, 73%.

However, there are exceptions to this rule. Pitchers with high strikeout rates are more likely to have higher strand rates since they can pitch themselves out of jams. On the other hand, pitchers that are simply not major league caliber will find their strand rates lagging below league average, though it is unlikely they will last for long in the league.

Coupled with BABIP, LOB% can empower baseball fans to discover pitchers who may see their ERAs skyrocket, or find the next breakout. However, it is always important to include qualitative analysis when using these statistics to ensure that the players in question did not make any adjustments that would account for slight variations in the numbers.


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