Alex Baltazar

What is causing the home run surge? A look into Baseball physics

JD Martinez hits a home run vs Houston. Boston Red Sox/Facebook

Hopefully everyone is recovering well from the emotional hangover the Houston Astros gave us after suffering from the gentlemen sweep generated by a tough Boston Red Sox team. But the show must go on.

In 2017, Major League Baseball was on pace to have the highest rate of homeruns in its history. MLB was getting a lot of negative publicity. People were assuming that the balls were being altered, or ‘juiced’, in order to make them go further. In 2014, the rate of homeruns per team per game was 0.86, in 2015 it rose to 1.01, in 2016 the rate increased to 1.16, and in 2017 the homerun rate was 1.26. Many pitchers complained that the balls were noticeably bouncier, and even Alex Bregman spoke on the topic by humorously replying to a tweet from a suspicious Trevor Bauer, “Relax Tyler, those World Series balls spin different (crying Emoji).”

MLB called upon physics Professor Alan Nathan from the University of Illinois to form a committee of fellow scientists to figure out exactly why baseballs were traveling further. Even though most of us are pleased to see booming homers at ballparks across the country, there are still historical aspects that we as fans still appreciate. “A homerun hit today, should mean the same thing as a homerun that was hit 50 years ago. Records that were set back then shouldn’t be broken in the current environment because of changes either in the players (the other juicing scandal), or changes to the ball. I think MLB is sensitive to that, and I think fans are sensitive to that as well.”, claims Professor Nathan. The idea is to try and preserve the purity and historical significance of the sport.

The committee led by Professor Nathan had no ax to grind with MLB. The committee worked completely independent from the league and had their full cooperation by having access to StatCast data. The committee also used their own independent labs to test the various physical properties of the baseballs. They even had access to the Rawlings factory in Costa Rica to analyze if any differences existed throughout the years in the production of MLB used baseballs. Here’s what they found.

Two questions were asked to explain the sudden spike in homeruns.

The first question asks, is the surge in homeruns due to a change in the launch conditions of the ball coming off the bat? Which can come from a higher exit velocity of the baseball, causing longer fly balls. Basically, this is asking if balls are now bouncier than before at the point of contact with the bat, explained by the physics equation dubbed the Coefficient of Restitution. The answer is no, the Coefficient of Restitution has remained the same throughout the years. In fact, the committee found that Rawlings actually exceeds the expected requirements for the limitations of the bounciness in their baseballs.

The second question is, are players hitting at more optimum launch angles at a given exit velocity? This also causes the ball to travel further. Basically, this is asking if hitters are altering their swing mechanics to achieve greater launch angle revolutions post contact with the baseball, causing more homeruns. Red Sox slugger, JD Martinez, is a prime example of this change in swing mechanics after altering his swing on the advice of his hitting coaches in SoCal. Interestingly, he was with the Astros during this transformation and was actually referred there by another former Astro, Jason Castro. The answer for this question is also no, optimum launch angles at given velocities are not seen as a collective effect big enough to increase the yearly average in homeruns.

What the committee did find is that there was a change in the Drag Coefficient when the baseball is in route to the stands. This means that baseballs are interacting differently with the air as they travel to homerun territory. The report states, “Procedures performed experimental tests at Washington State University and the mathematical analysis of StatCast data indicate that the Drag Coefficient has changed by approximately 0.0153 since 2015, an amount sufficient to have caused the home run surge” But how? The committee tested changes in the size, texture, weight, and seam height in the baseballs, but found no correlation with any of a baseball’s physical properties.

Basically, we still don’t know exactly what is causing the surge. We know it’s not the Coefficient of Restitution, or bounciness. We also know that it’s not a collective change in launch angles, causing the balls to travel further. Lastly, we also know that the physical properities of baseballs have remained the same. Rather, it has something to do with how the ball is suddenly more aerodynamic, or the decrease in Drag Coefficient. This could mean that there must be something the committee missed as far as testing methods, or even overlooking another component of the baseball that has been yet thought of being experimented. As of now, the cause is pure speculation. We at least know what it isnt. 

Baseballs are still being tested and an interesting hypothesis has now surfaced. What if the core of the ball, or the ‘pill’, is somehow all of the sudden slightly off centered? This causes the ball to spin further into the direction its going, also making it travel further. Rawlings is currently creating baseballs with off centered pills to test this hypothesis.

You can access the Report of the Committee Studying Home Run Rates in Major League Baseball here.

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A WEEKLY REVIEW OF CRENNEL'S COACHING

Now my job: Texans feast on Lions

Photo by Getty Images.

Thanksgiving is full of tradition. There's the typical family gathering, large meal, and of course, football. Sometimes, new traditions are added and old ones are retired. I think the Texans did both in their impressive 41-25 win over the Lions in Detroit. Old traditions were carried on (Lions losing on Thanksgiving), some were put to rest (Texans not being able to get turnovers), and new ones were started (multiple passing touchdowns by Deshaun Watson in six straight games).

The fact that this defense got three turnovers in the game was unbelievable! They got all three in the first quarter within the span of eight plays. JJ Watt's pick-six was insane. He went for a batted ball, ended up catching it, and ran it in. They forced Jonathan Williams to fumble on the Lions' very next play from scrimmage and recovered it. On the Lions' next possession, the Texans recovered yet another fumble after the challenge was reversed. Great call by the coaching staff to challenge and win. The defense looked good. Tyrell Adams stood out because he was in on those two fumbles, made 17 total tackles with 14 of them being solo tackles. They also brought pressure that seemed to make Matthew Stafford very inaccurate and resulted in four sacks. I give defensive coordinator Anthony Weaver credit for knowing he needs to blitz to get pressure, but the run defense has to improve.

The offense kept the tempo up in this game as well. The spread and hurry-up were used to keep the Lions already staggered defense off balance. Knowing the Lions were without a couple defensive backs, I thought it would be the perfect marriage of their defense and the Texans' offense. A buddy asked before the game about the line (Texans -3.5) and the over/under (52.5). I told him bet the Texans and the over because neither team can play defense and both have good quarterbacks. Offensive coordinator Tim Kelly put together another good game plan and Watson executed it flawlessly. One route combo I saw later on in the game I particularly enjoyed. Two receivers were tight to the left side. Cooks ran a hook/curl and settled in the middle of the zone while Fuller ran a vertical route. Duke Johnson ran a swing route to that same side. It left Cooks wide open as the attention went to Johnson in the flat, Fuller deep, and the action to the other play side. Route combos are important because it gives the quarterback different reads as he goes through his progressions and lets him pick apart the defense based on what he sees. Combine that with Watson's play and the way Kelly has changed his play calling now that he's liberated from he who shall not be named, we're seeing a beautiful thing.

As good as things were, there's still room for improvement. The defense gives up way too many easy yards, both run and pass. They can't get pressure bringing only four and will often give up big plays if the blitz is picked up. Plus the run defense is still an issue as evidenced by the Lions' first possession of the second half. The Lions ran the ball 10 plays straight for a total of 58 yards on that drive. Utterly ridiculous! Watson was good (17/25 318 yards and four touchdowns), but he missed two more touchdowns with passes slightly off, and continues to hold onto the ball too long at times. The difference between these two issues I've presented here is the fact that Watson has so played well, his "issues" are minor and very correctable, while the defense is terrible and there's no easy fix in sight. But let Romeo Crennel and Anthony Weaver tell it, they're getting the most out of these guys and they're playing disciplined.

The thought that this team may actually creep into the playoff picture may take shape better after next week if they can beat the Colts. I doubt it, but it is getting interesting. Let's see what else happens around them because they need help getting there.

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