Mandatory Credit: Brad Penner-USA TODAY Sports
I recently published an article, citing work from Jared Diamond of the Wall Street Journal, on how in 2021, the most successful (as determined by postseason qualification) teams were generally those that did the best job at minimizing ground balls.
A friend of mine asked a critical question: What does this really mean? Yes, teams that most effectively avoided hitting the ball on the ground comprised the preponderance of 2021 playoff teams. But does hitting the ball in the air make a team better offensively by significantly impacting other metrics? Let’s take a look.
First, here is some perspective. How many ground balls does a percent, or tenth of a percent, equate to over a season? Using very rough numbers:
- Average team outs in a game (excluding extra innings and considering home team wins with 24 outs): 25
- Team hits in a game: 10
- Team strikeouts in a game: 10
- Balls in play in a game: 25
- Balls in play over a season: 4,050
- A percent equals 40 balls in play in a season
- A tenth of a percent equal 4 balls in play in season
The table below shows the seven teams that hit the lowest percentage of ground balls in 2021, and how they ranked in other offensive metrics.
| Team | GB% | wRC rank | wRC+rank | Total runs scored | Exit Velocity rank | OPS rank | OPS rank |
| San Francisco* | 39.7% | 4th | 5th | 6th | 16th | 4th | 5th |
| Atlanta* | 40.3% | 10th | 13th | 8th | 7th | 8th | 15th |
| LAD* | 40.4% | 5th | 7th | 4th | 5th | 6th | 8th |
| Boston* | 40.4% | 3rd | 6th | 5th | 2nd | 3rd | 7th |
| Toronto | 40.4% | 2nd | 2nd | 3rd | 1st | 1st | 1st |
| St. Louis* | 40.5% | 18th | 15th | 20th | 13th | 15th | 12th |
| Houston* | 40.6% | 1st | 1st | 1st | 6th | 2nd | 2nd |
*playoff team
The chart shows that the correlation is not perfect between ground ball percentage and rank in other key offensive metrics. The teams that kept the ball in the air best (with the exception of the Cardinals) ranked in the top half of baseball across the other key metrics (save for the Giants’ exit velocity).
Going back to the original question: what does success in ground ball percentage actually mean? I think it’s safe to say that hitting the ball in the air contributes to, but does not predict a team’s offensive success.
The Astros, using the rough math above, hit about 400 more ground balls than did the Giants, yet they ranked higher in every other metric. The Astros (.303) had a higher BABIP than the Giants (.295), so perhaps Dusty Baker‘s team placed their hits better, or simply hit in better luck. Houston also had a higher hard-hit percentage (33.2%) than San Francisco (31.6%) despite hitting more balls on the ground.
In summary, it’s obvious that ground balls do not lend themselves to as many positive outcomes as do balls hit in the air. However, ground ball percentage, as evidenced by rank across other key metrics, warrants further analysis, and on its own can be inconclusive.
Also, using the endpoint of success as defined by postseason qualification discounts other very important factors, such as pitching and defense (we all know the Giants pitched well in 2021, for example).
Final note: how about those Blue Jays? They had quite an offense in 2021, and though they were alive until the last day of the season, they missed the playoffs. Their team ERA was 10th in baseball (bullpen 16th). If they can add some pitching, particularly in the bullpen, they will provide stiff competition for the Rays, Red Sox, and Yankees in the coming years.
