what is rDiff in baseball

What is Run Differential (RDiff) in Baseball?

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When trying to determine how good a baseball team really is, the most effective way to do it is by simply watching the team play, especially against other quality opponents. After all, there is a reason the game is played on a field and not on paper. However, your eyes can lie to you.

Sometimes, the numbers can tell you what your eyes can not. Doing a deep dive into statistics can give a fan or coach a better sense of how good a team really is.

A statistical category that many experienced baseball analysts point toward when determining the quality of a team is RDiff.

In baseball, RDiff stands for run differential. Run differential is the difference between the total number of runs a team scores and the total number of runs it allows.

For example, if a team scores a total of 500 runs in a season and allows 400 runs, their run differential is +100. If they score a total of 400 runs in a season and allow 500, their run differential is -100.

In this article, we look at RDiff and its role in America’s pastime as well as why some baseball analysts put more stock into it than others.

Is Run Differential a Meaningful Statistic?

Anyone who has studied baseball long enough understands that not all stats are created equal. Some are more meaningful than others. So where does RDiff stand when it comes to meaningful statistics?

Run differential is meaningful because it gives valuable insight into the quality of a team and sometimes serves as a tiebreaker when determining playoff positions.

Some people believe that run differential is a meaningful statistic when analyzing a team’s likelihood of making a playoff run.

Teams that have a high run differential and a good record have clearly dominated their opponents during the regular season; therefore, one can conclude that they are better than most opponents they play from a talent standpoint.

On the other hand, teams with good records and lower run differentials may signal that a team has overachieved throughout the season.

Others argue that winning teams with lower run differentials are more likely to make long playoff runs. Usually, teams that fall into this category have played in and won a lot of close games.

Since there are more close games than blowouts in the playoffs, analysts often argue that these teams are more prepared for a playoff run than the teams with higher run differentials.

As mentioned, RDiff is sometimes used as a way to break ties when looking at playoff seeding. Currently, the MLB does not use run differential as a way to break ties when it comes to the playoffs.

However, many amateur leagues may use this as a tiebreak method in order to reward teams that have outplayed their opponents all season long. Other methods of breaking ties are head-to-head records, total runs scored, total runs allowed, among several others.

What is a Good RDiff?

When analyzing statistics, it is always important to know a benchmark for success.

A good run differential is anything in the positives. A great run differential is at least the same number of games played.

For example, if a team plays 50 games, a run differential of +50 would signal that they are having an average season. Doubling or even tripling the number of games played would be considered exceptional.

What is the Highest RDiff in MLB History?

To figure out the team with the highest run differential ever in the MLB, we have to dust off the history books and go all the way back to the late 1800s when Major League Baseball began.

In 1884, the St. Louis Maroons had a run differential of +458 through the regular season which is the highest in MLB history.

The most impressive thing about this record is that they did it in 114 games, 48 games fewer than MLB teams play today. They went 94-19 that year for a win percentage of .832.

The 2022 Los Angeles Dodgers had one of the best run differentials in MLB history this past season. They scored 334 more runs than their opponents which puts them 13th on the all-time list.

This Dodgers team was the favorite to win the World Series and was talked about as one of the most dominant teams the league has ever seen. All of their statistics supported these claims, but their early playoff exit confirmed why many do not put all of their faith in numbers.

The Dodgers lost to the San Diego Padres in the Divisional round of the playoffs after winning 111 regular season games. Some would argue that this supports the idea that run differential does not matter come playoff time.

However, the Houston Astros, the eventual World Series champion, was third in the league in run differential.

What is the Lowest RDiff in MLB History?


To find the team with the lowest RDiff ever in the MLB, we need to look in the same part of the history book as we did to find the MLB’s most dominant team.

In 1899, the Cleveland Spiders had a run differential of -723 through the regular season. This is the worst run differential in MLB history.

The Spiders won only 20 of their 154 games that season for a win percentage of .130.

The Detroit Tigers have had two seasons in the 2000s that have ranked them on the list of worst run differentials in an MLB season.

Their 2003 season where they scored 337 runs fewer than their opponents ranks 18th all time. Their 2019 season saw a run differential of -334 ranks 21st all-time.

The Tigers were considered to be one of the worst franchises in the MLB in 2019, however, their struggles that year and a few years before led to several years with high draft picks, and the team appears to be on the upward trend.

Related Questions

Is RDiff Calculated as a Total or an Average Per Game?

RDiff can be calculated either as a total or as an average. When it is calculated as an average, a team’s only goal is to have a positive number. The more dominant teams have a number higher than +1 when calculated as an average per game.

What is the Most Wins in an MLB Season?

The 2001 Seattle Mariners and the 1906 Chicago Cubs are tied for the most wins all-time in an MLB season with 116. Some consider the Cubs to hold this record because they played 155 games compared to the Mariners’ 162 total games played.

What is Win Percentage?

Win percentage is the percentage of games a team wins in a season. It is written in the form of a three digit decimal. For example, a team that has 75 wins and 25 losses would have a win percentage of .750. It is often expressed as W% in the standings.