Physics in Real Life: Bombs Hidden within the Bender

Hitters are often told by their coaches to “hunt the fastball,” to look to drive a fastball rather than seek out a breaking ball that exchanges velocity for movement. However, amid the Moneyball Era, a group of baseball misfits were already looking to the future and what would become the Statcast Era. In 2003, professors Gregory S. Sawicki, Mont Hubbard, and William Stronge, published their paper “How to hit home runs: Optimum baseball bat swing parameters for maximum range trajectories.” One of their findings was that “[the] optimally hit curve ball will travel farther than both the fastball and knuckleball.” This raises the question: Should hitters look to hit the curveball instead of hunting fastballs? (Due to the lack of knuckleballers in today’s game we will only examine hitting curveballs today. Sorry, Mickey Jannis.)

To find the answer to this question, we will look at what are probably the two most fundamental aspects of hitting: contact and power. First, we’ll look at contact. If we were to poll baseball coaches from around the nation to give their thoughts on looking to drive curveballs over fastballs, they would probably give the objection that curveballs are more difficult to contact. Congratulations, hypothetical coaches, you would be correct. With a whiff rate of 31.2%, batters completely miss curveballs almost twice as often as fastballs (whiff rate of 17.7%). On top of that, in general, hitters are more likely to make better contact on fastballs than curveballs, as fastballs lead in basically every contact statistic. Not to mention, hitters are more likely to hit a home run off a fastball than off a curveball.

Before we completely write off hunting curveballs, let’s remember something: we haven’t actually disproved Sawicki et al.’s finding. According to the scientists, an “optimally [emphasis added] hit curveball will travel farther, because of beneficial topspin on the pitched curveball that is enhanced during impact with the bat.” The topspin of a curveball as released by a pitcher translates to backspin off the bat. This backspin increases the amount of time the ball spends in the air, which allows the ball to travel farther, leading to better contact metrics and therefore better power. When looking at the top 10% of hardest hit balls for the two pitch types, curveballs and fastballs flip their rankings in every statistical category except for average exit velocity, which could be attributed to the frequency of ground balls off fastballs in this subset (36.7%) compared to curveballs (29.5%). As expected, the home run rate off the best-contacted curveballs is higher than those of the best-contacted fastballs (24.3% vs. 23.5%). Simply put, if an MLB hitter really gets ahold of curveball, the pitcher will probably be wishing he threw his heater instead.

Surprise, surprise, physics remains the same, even after almost two decades. But what does that mean for baseball? Should hitters start hunting the curveball in lieu of the fastball? The short answer is maybe. There is a tradeoff when trying to hit a curveball. Hitting a curveball optimally is extremely difficult, and hitters are more likely to whiff at a curveball than a fastball. A hitter is more likely to contact a fastball, but curveballs have more power potential. Basically, a hitter is more likely to get on base by hitting a fastball, but a curveball has more capacity for extra bases. Hunting one pitch over the other may be situational. For example, looking for the fastball when leading off, and sitting curveball with runners on base. Ultimately, this is an area for further research and discussion.

There is value in training to hit the bender. Just ask Ronald Acuna Jr., whose 7 home runs off curveballs led the majors in 2019.Thanks to pitching machines that throw more than just your run-of-the-mill fastball, training to hit the bender is now a very plausible. Additionally, with the increasing use of breaking balls and subsequent decreasing usage of fastballs, hitters who learn to hit the curveball proficiently make themselves more versatile and more lethal at the plate. If anything else, it’s simply more fun to hit bombs, and curveballs are ripe with potential to be put over the fence, even more so than fastballs.