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Hitting Homers

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Diamondbacks homers are trending downward. Let’s focus on the impact of homers in the 2021 season and possible improvement next season.

Daulton Varsho at the plate.
Daulton Varsho at the plate.
Photo by Norm Hall/Getty Images

A downtrend happened in the last two seasons.

At the top level, the homers per PA fell from .035 in 2019 to .023 in 2021. Because in 2022 many of those players will not be playing for the Diamondbacks, let’s look at 12 position players who will likely return to play for the Diamondbacks. For those players, the following table shows that their homers per PA fell, with the exceptions of Josh Rojas and Daulton Varsho.

Diamondback players expected to play in 2022. Data from Baseball Reference.

The most likely reason is the baseball was changed to a lighter core which reduced homers. This season half the baseballs were lighter. Next season all the baseballs will be lighter. The downward trend will likely continue.

Explanations for low homer totals.

The following table shows that the Diamondbacks consistently did not hit as many homers as their fundamentals would predict by comparing actual homers to expected homers, xHR. My view is that the difference was more than just bad luck.

Diamondbacks expected to play in 2022. Data from Baseball Savant.

Perhaps Chase field reduces the number of homers. The park factors for Chase Field show its’ impact – 11% less homers and more hits (43% more triples, 10% more doubles, and 3% more singles). See the following table.

Data from Baseball Savant.

Although Chase reduced Diamondback homers in 2019, in 2020 and 2021 the impact on homers per PA was much less significant. It is to be determined whether Chase will have an impact in 2022.

Data from Baseball Reference.

When do the Diamondbacks hit homers?

The following table shows that 35% of homers were hit with a 2-strike count, and 47% of homers were hit with men on base.

Data from Baseball Reference.

My view is that the batters’ reasoning is that with men on base, a homer that falls short will nevertheless be considered successful if it advances the runners and allows a runner at third to score. An additional reasoning is that a failed homer takes a double play off the table.

As for why two strikes, perhaps the batter predicts the location will be over the plate in an attempt to strike him out. Correctly anticipating the pitch location would result in more homers.

How much improvement is needed?

Let’s look at this question on two levels - at a top level and at a more detailed level.

Top Level. In 2021, the Diamondbacks hit .889 homers per game, which ranked 29th in the Majors. To improve to the median (1.222 homers per game) would require increasing homers by an average of 37.5% per game. Adding to the difficulty is Eduardo Escobar, the team leader in home runs, was traded away. My view is that achieving that much increase would be challenging.

More Detailed Level. For the 2021 Diamondbacks, let’s look at runs-per-homer and homers-per-game for three types of games:

  • This season 40.4% of won games had a game winning margin of less than or equal to runs scored by homers (homers made a difference).
  • This season, 59.6% of won games either had zero homers or the winning margin was greater than the runs scored by homers (homers did not matter).
  • This season’s lost games.

The following table shows runs-per-homer, homers-per-game, and total-runs-per-game- from-homers for those three types of games.

Diamondbacks, 2021 season. Data from Baseball Reference.

A likely explanation for increased runs per homer in won games is that won games had more baserunners.

When games were won and homers made a difference, the 1.67 homers per game was twice as frequent as the 0.70 homers per game in lost games. For perspective, how many teams averaged at least 1.67 homers for game for the entire season? None. That tells me that consistent 1.67 homers per game would be nearly impossible for the Diamondbacks.

The key takeaway is that won games with impactful homers had 1.86 more runs per game than in lost games. This season the Diamondbacks hit 613 line drives, which was four times as many as their 144 homers. My gut tells me that increasing the frequency and effectiveness of successful line drives could increase runs per game by that same amount, with the additional benefit of more consistency than hitting homers. The following table compares line drives and fly balls with homers separated from hits.

Diamondbacks, 2021 season. Data from Baseball Savant.

Summary of My View.

Homers are in a downward trend for the Diamondbacks. It was encouraging that 35% of homers were hit with 2 strikes, and 47% of homers were hit with men on base. It was discouraging that Chase Field negatively impacts homers.

In games that homers had a positive impact, they contributed 2.90 runs per game, which compared favorably to their contribution of 1.04 runs per game in lost games. Nevertheless, for the Diamondbacks to improve to a .500 team would require increasing homers per game by a challenging 37.5%.

The Diamondbacks hit four times as many line drives as homers. As an alternative to a single minded focus on increasing homers, the Diamondbacks could more consistently score runs by increased frequency and effectiveness of line drives.