What Does LOB Mean in Baseball Terminology?

Michael Claunch

Baseball is a statistically driven sport, with a variety of statistical parameters used to evaluate the performance of individual players and teams. LOB, or runners left on base, is one statistical concept that is frequently cited when discussing a certain game or used to describe tendencies in team performance over a longer period. Since the stat is relatively complex and dependent on an understanding of baseball rules, many casual fans are unaware of its real meaning and relevance.

This guide will answer the most important questions about this metric and try to explain what does LOB mean in baseball and what can be deducted about a team based on it.

What does LOB stand for?

Runners left on base or LOB are players who remain on the field at the end of an inning without being tagged or otherwise forced out on the last play. The totals for each inning are then added to get LOB for an entire game, and this can be done for each participating team. It’s also possible to use LOB to analyze a team’s performance over several games or an entire season, in which case per game averages are commonly used.

It’s important to clearly define which runners count towards the LOB total. Only those runners that haven’t been retired are considered to be left on base, and in the case of double play or triple play, multiple players who are seemingly on base could be eliminated from this calculation. Obviously, LOB for a single inning can take any value from 0 to 3, since even with bases fully loaded, one runner must be retired in order to complete the inning.

Now that we clarified what LOB stands for, it’s time to think about the true implications of this statistical parameter and insights about team quality that can be derived from it.

What is LOB baseball stat correlated with?

It’s not hard to understand that teams that manage to get more runners on base will also have more runners stuck at one of the bases when the inning ends, and thus a higher LOB value. In other words, offensively talented teams that score a lot of points tend to also have higher LOB. This tendency is more pronounced when looking at season numbers since fluctuations from game to game are evened out when the sample size is increased.

On the flip side, a low LOB of the opposing teams might be indicative of high-quality pitching. This is also very logical since good pitching teams allow fewer runners to reach base, decreasing the likelihood that some of them will remain on the field after the third out. Thus, just like good offensive teams tend to have high LOB, good defensive teams tend to keep the opponents LOB at a low level during a season.

lob baseball stat
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Is LOB indicative of winning?

From the analysis presented above, it’s clear that LOB is in correlation with offensive performance both in a single inning and any other period. In turn, this means that teams with high LOB will typically score a lot of points over a season and have a solid chance of being good in the standings. Still, it shouldn’t be forgotten that runners left on base represent missed opportunities rather than scoring chances, so the correlation with winning may not be as direct as it seems.

That’s especially the case when talking about a single game. A losing team with a high LOB can rightfully point to numerous opportunities to score more runs that it couldn’t capitalize on. In particular, fans like to point to LOB baseball stat as proof that their team was superior even in defeat, which is partially true. LOB is just one metric that contributes to a bigger statistical picture, and placing too much weight on it in terms of predicting future performance is not advisable.

What is considered a normal LOB for a professional team?

In almost every baseball game, there will be some runners left on base, but their number can vary greatly. In Major League Baseball, an average team can be expected to record season-long LOB between 6 and 7, with Washington Nationals leading the league in 2021 with 7.31 LOB and Cleveland ranking last with a 6.09 average. In terms of historical record, the highest LOB in a season dates back to 1941 when the St Louis Browns recorded 1334 or 8.5 per game. Meanwhile, San Diego Padres has 5.96 runners LOB per game (965 in total) during the 2016 season for the lowest season average in MLB history.

While the averages don’t deviate a great deal from the mean, there have been numerous instances of much higher LOB in a single game, either by one team or both. The record for a nine-inning game is 20, set in 1956 by the New York Yankees, while the highest number of runners left on base in a game of any length is 27, recorded by Atlanta Braves in 1973. If that seems high, it’s even more shocking to know that the highest combined LOB for both teams in a game is 45 LOB, which occurred in 1974 and then again in 1991.

Should fans care about LOB baseball stat?

There is no doubt that LOB accurately describes one aspect of a game, which is why this statistical concept has a legitimate place in baseball analytics. It points to opportunities left on the field and may sometimes explain why a good hitting team lost a game. Season-long LOB is likely correlated with the offensive power of a team, but it’s otherwise random since no systemic factor is causing runners to remain stranded on basepaths at the end of an inning.

Because of this, the predictive power of this metric is relatively poor, and it’s not wise to use it as the primary indicator of future winning percentage. LOB is just one descriptor of a team’s performance, and while it may be tempting to lean on it to explain why a certain team is losing more than expected, in isolation it can’t tell you much.

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