Description:

Left on Base Percentage (LOB%) measures the percentage of base runners that a pitcher strands on base over the course of a season. Most pitchers have LOB%s around league average (which is approximately 70-72%, depending upon the season), and pitchers that deviate from that average tend to see their numbers regress towards league average in the future. In other words, if you see a pitcher with a 60 LOB%, they are letting lots of runners score and so their ERA will be high, but the odds are that they will strand more runners in the future and lower their ERA.

The only case where pitchers have been shown to have some control over their LOB% is with high strikeout pitchers. Pitchers that record high numbers of strikeouts can pitch their way out of jams more easily than a pitcher that relies upon their team’s defense, so they are able to maintain higher than league average LOB%s.

Context:

2010 LOB% Rates

Things to Remember:

- Use this statistic in conjunction with others, specifically BABIP and HR/FB. It’s a good way to get an idea of if a pitcher is under- or over-performing and likely to regress.

Links for Further Reading:

Ten Things I Didn’t Know – Hardball Times

Left on Base – Hardball Times