Stat of the Week: The Importance of Defense

By MARK SIMON

On ESPN’s broadcast of the Monday Night Baseball game between the Giants and Astros, Tim Kurkjian noted that he had studied the connection between defense and winning and found that bad defensive teams are usually losing baseball teams, unless extenuating circumstances exist, such as a high-strikeout pitching staff.

We frequently look at the relationship between defense and winning and Tim’s comments inspired us to give it another go. We decided to look at team Defensive Runs Saved totals for the last seven seasons, which encompasses the time covered by our new PART system.

This image shows team Defensive Runs Saved graphed against winning percentage from 2013 to 2019. The correlation coefficient is .38, indicating some relationship between the two stats.

Of the 16 seasons with the fewest Defensive Runs Saved in that span, only the 2013 Tigers and 2019 Mets had a winning record (and for much of the season, the Mets didn’t). Of the 40 lowest Runs Saved totals, there are nine teams with winning records. Seven of those nine ranked in the top three in their league in either runs scored (meaning they overpowered opponents with their offense) or pitcher strikeouts (they limited balls in play), which gets to what Kurkjian was talking about.

The 2015 Twins, who went 83-79, finished eighth in the AL in runs scored, last in pitcher strikeouts, and second-to-last in the American League in Runs Saved, are one of the aberrations here. The other is the 2016 Tigers, who were sixth in the AL in runs scored and 11th in pitcher strikeouts. A key to their 86-75 record was an unusually good record in one-run games (26-17), a stat that greatly fluctuates from year-to-year.

On the other end of the leaderboard, of the top 41 team seasons in Runs Saved since 2013, 28 were by teams with winning records. If we narrow the scope to 2016 to 2019, 16 of the 18 team seasons with the most Runs Saved came from winning teams.

The usual caveats apply about correlation not necessarily equaling causation. But we challenge you to find a reason to not prioritize defense. As we've said before, even in an era in which strikeouts and home runs dominate the game, defense is still very important.