Can Diamondbacks Hang On to Make Postseason With 92 ERA+?

We take a look through MLB history to see how many teams make the postseason or win the World Series with such below average pitching.

Arizona Diamondbacks pitcher Merrill Kelly (29) is taken out of the game by manager Torey Lovullo at Chase Field on Aug. 31, 2024, in Phoenix. / Owen Ziliak/The Republic / USA TODAY NETWORK

It's no secret to anyone that has followed the Arizona Diamondbacks closely this year that their offense has been the driving factor in their success. The 78-61 record, and current NL Wild Card position has been built on a league-best offense, overcoming a pitching staff that ranks very near the bottom of MLB.

The Diamondbacks lead MLB in runs scored per game with 5.45 and their 114 OPS+ ranks fourth. The team has allowed 4.78 runs per game however, which is the 5th worst total. Their ERA+ is 92, which ranks 27th in MLB.

If the Diamondbacks remain at or below their current 92 ERA+, they would be only the fourth team in major league history to make the Postseason with a 92 or lower ERA+.

The three teams to do it previously were the 1913 Philadelphia Athletics, the 1981 Philadelphia Phillies, and the 1981 Milwaukee Brewers. Report link.

Baseball historians will immediately note the significance of those seasons. 1981 was a strike-shortened season in which teams only played between 107-109 regular season games. Both the Phillies and Braves were bounced in the first round of the playoffs.

1913 was the middle of the "dead ball" era in MLB, when league ERA typically fluctuated between 2.50-3.50 and unearned runs were about three times as many as they are today. The Athletics won the World Series that year.

In other words, no modern team, playing in a full major league season, has made the playoffs with an ERA+ of 92 or lower. The Diamondbacks would be the first to do it in 111 years.

Before I go any further, a word about ERA+. Run scoring in MLB has fluctuated greatly over its history. Posting a 3.50 ERA in a league that averages a 4.00 ERA does not have the same value as a posting a 3.50 ERA in a league that has a 4.50 ERA. Clearly the latter would be more valuable.

Likewise, posting a 3.50 ERA pitching home games in a park that heavily favors pitchers (such as Oracle Park in San Francisco) would not have the same value as posting the same ERA calling Coors Field in Denver home. Most fans have an intuitive sense of this, but it's not really possible to make that value adjustment in one's head.

That's where ERA+ comes in. This metric measures ERA against the league average, and makes adjustments for Ballpark factors. 100 = league average. The higher the better. It can be found easily at both the league and team pages at baseball-reference.com. If you want to know more about the formula you can go to this wikipedia link.

Last year the Diamondbacks finished the year with a 98 ERA+. It should be noted that the next worst ERA+ number for any team that's in a playoff position is 98 by the Baltimore Orioles. The New York Mets are knocking on the postseason door loudly and have a 99 ERA+.

So what does it look like if the Diamondbacks' ERA+ improves over their final 23 games? Some improvement is possible of course, especially if Zac Gallen and Merrill Kelly can re-discover their form over their last four to five starts. But getting from 92 to 94 or 95 is likely the upper limit with so few games remaining.

Expanding the view to show teams that had an ERA+ of 95 or lower, the number of postseason teams expands from three to nine, with the most recent being the 2005 Yankees and Padres.

Team ERA+ 95 or lower Postseason teams / Jack Sommers

This table also helps illustrate the point made above about context and relevancy when it comes to measuring against league averages. The Padres' unadjusted, or raw ERA is 0.41 lower than the Yankees, yet the ERA+ is the same.

That is because of two factors. In 2005 the NL did not have the DH. The American League ERA was 4.68 that year compared to the National League's 4.22 ERA. Compounding this, Petco Park played as one of the most pitcher-friendly parks in MLB, while Yankee stadium was neutral.

The 1913 Athletics remain the only team to have won the World Series with a team ERA+ below 95. The 1914 team won the pennant but lost the World Series.

Questioning whether the Diamondbacks can make it back to the World Series, or even hang on to make the postseason with the current state of the pitching staff is hardly a novel thought process. Most people watching the team closely are thinking the same thing.

But this research shows just what kind of history the Diamondbacks are up against. Records and precedents are made to be broken. If they manage to pull it off, then it will be just that more remarkable.