The Bat Too Hot for MLB. Why the Marucci Cat 5 is Banned


The Marucci Cat 5 baseball bat has been the subject of controversy in youth baseball leagues. Manufactured in Baton Rouge, Louisiana by Marucci Sports, the Cat 5 has gained notoriety for its performance-enhancing capabilities and was eventually banned by multiple governing organizations including the NCAA, NFHS and USSSA leagues.

Introduced in 2008, the Cat 5 featured a one-piece aluminum alloy barrel designed to optimize the trampoline effect and maximize ball exit speed. Early player feedback praised the bat’s “hot out of the wrapper” performance and “massive sweet spot.” However, as more young players began using the Cat 5, concerns emerged about its potential to give hitters an unfair competitive advantage.

This article provides an overview of the Marucci Cat 5 baseball bat, examining why it gained popularity, how its design impacted performance, and the reasons various leagues ultimately prohibited its use in competition.

History of the Marucci Cat 5

The Marucci Cat 5 baseball bat was first introduced in 2009 by Marucci Sports as their inaugural one-piece alloy bat. According to the Marucci Sports article “Evolution of the CAT Baseball Bat Line”, the Marucci Cat 5 was named after a Category 5 storm, representing the bat’s high-performance design.

Marucci Sports was founded in 2002 by two former Major League Baseball players, Kurt Ainsworth and Joe Lawrence. As described in “The Marucci Story” article on their website, Marucci started out hand-crafting wood bats for professional players before expanding into metal bats like the Cat 5.

The Cat 5 was Marucci’s first bat designed specifically to meet the new BESR (Ball Exit Speed Ratio) standards that went into effect in high school and college leagues in 2009. It featured a one-piece AZ105 alloy construction with vibration dampening technology called “Anti-Vibration Taper” or “AV2” designed to reduce negative feedback on the player’s hands.

Overall, the Cat 5 represented Marucci’s initial foray into high-performance alloy bats and was optimized for power and speed according to the new BESR standards at the time of its release.

Performance of the Marucci Cat 5

The Marucci Cat 5 quickly gained popularity among players for its exceptional exit speed and pop. Many players reported significant performance gains when using the Cat 5, with some experiencing exit velocities over 100 mph (source).

The one-piece AZ105 aluminum alloy construction gave the Cat 5 a responsive and stiff feel through the zone. This optimized the trampoline effect, resulting in hard hit balls with more carry. Marucci designed the Cat 5 with a “ring-free” barrel, which removed mass from the bat’s sweet spot and directed more energy to the ball on contact (source).

Many considered the Cat 5 to be among the hottest aluminum bats ever produced. The balance, swing speed, and explosive power it provided led to exceptional exit velocities and home run distances. This superior performance is ultimately what led to its banning across multiple leagues.

Marucci Cat 5 Banned by NCAA

The NCAA banned the use of the Marucci Cat 5 bat in college baseball games starting in 2011 due to performance and safety concerns. According to the NCAA’s prohibited bat list (NCAA Prohibited BBCOR Baseball Bats), the Cat 5 failed to meet the Bat-Ball Coefficient of Restitution (BBCOR) performance standard adopted that year.

The BBCOR standard was implemented to regulate the performance of non-wood bats and reduce ball exit speeds for safety. Prior to BBCOR, collegiate baseball used the Ball Exit Speed Ratio (BESR) standard. However, there were concerns that technology advances allowed some BESR bats to perform too close to wood bats.

The Marucci Cat 5, known for its large sweet spot and high-performing barrel, produced exit velocities that exceeded the limit allowed under the new BBCOR rules. As a result, the NCAA banned Cat 5 bats to ensure a wood-like performance standard was maintained across college baseball.

Marucci Cat 5 Banned by NFHS

The National Federation of State High School Associations (NFHS) banned the 33-inch model of the Marucci Cat 5 BBCOR baseball bat in high school play starting in 2012. The NFHS sets the rules for high school baseball and softball in the United States.

The main reason the NFHS banned the 33-inch Marucci Cat 5 was due to performance concerns. High school leagues aim to maintain a level playing field by regulating bat specifications. There was suspicion that the Marucci Cat 5 allowed players to hit the ball with more speed and power compared to other BBCOR certified bats. This gave an unfair performance advantage.

Although the Marucci Cat 5 was BBCOR certified and met the -3 length to weight ratio requirement, the NFHS still deemed it necessary to issue a ban. Protecting the integrity and fairness of competition was the priority.

Specific details on test results and data that led to the NFHS ban are unclear. However, the Marucci Cat 5 was consistently one of the top performing BBCOR bats on the market during that time period. It generated exceptional exit speeds and power numbers compared to competitors. This likely contributed to the NFHS deciding to take action and remove the bat from play.

Marucci Cat 5 Banned by USSSA

The United States Specialty Sports Association (USSSA) banned the Marucci Cat 5 bat in 2011 due to safety and performance concerns (USSSA). USSSA tests bats for performance and compliance with BBCOR standards. During testing, the Marucci Cat 5 was found to exceed the BBCOR performance limits, allowing players to hit balls at dangerously high speeds.

Specifically, USSSA determined that the Cat 5 had an illegally high trampoline effect beyond the BBCOR limit of 0.500. This trampoline effect gave batters a performance advantage by increasing the bat’s bounce and allowing the ball to be hit harder and farther. USSSA bans any bat model that exceeds BBCOR limits in order to maintain fairness and safety in competition.

Marucci Cat 5 Banned by MLB

The MLB decided to ban the use of the Marucci Cat 5 in all professional games and tournaments in 2017. This decision came after years of speculation over the bat’s performance and safety.

The MLB conducted extensive testing on the Marucci Cat 5 and determined that the one-piece alloy bat posed risks to pitcher safety. The bat was shown to increase the speed of the ball coming off the bat significantly compared to traditional wood bats.

This increase in exit velocity meant that fielders had less time to react to batted balls, and pitchers were more at risk of being struck by comeback line drives up the middle. MLB cited concerns over player safety as the primary reason for banning the bat.

Additionally, the MLB determined that the bat gave hitters an unfair performance advantage over pitchers. While the Marucci Cat 5 was certainly impressive in boosting batted ball speeds, the MLB decided those gains went against the spirit of fair competition.

Ultimately, by banning the bat, the MLB aimed to maintain the balance of play between offense and defense while also protecting pitcher safety. The Marucci Cat 5 was deemed to provide hitters too much of a competitive edge and pose too much injury risk to pitchers.

Safety Concerns

One of the main reasons the Marucci Cat 5 was banned was due to safety concerns around injuries. Metal baseball bats like the Cat 5 have faced scrutiny due to their potential to hit balls at dangerously high speeds, increasing the risks of serious injuries for pitchers and infielders.

According to a study by the American Academy of Pediatrics, metal bats like the Cat 5 can cause baseballs to rocket off the bat at speeds up to 114 mph, versus 98 mph for the fastest hit with a wooden bat. These high ball speeds give fielders less reaction time to protect themselves.

The study found that infielders are at highest risk of injury, with most injuries occurring to the pitcher’s head and torso. Metal bats were shown to contribute to a rise in eye injuries and even fatalities among pitchers at the youth level in particular.

These safety risks are why organizations like the NCAA, NFHS, USSSA, and others decided to ban ultra high-performing metal bats like the Cat 5. While they clearly provide hitting advantages, the safety of players was deemed more important.

Performance Enhancing

One of the main reasons the Marucci Cat 5 has been banned by many youth baseball leagues is due to concerns that it provides players with an unfair performance advantage. The Cat 5 utilizes a number of patented technologies that Marucci claims increases the bat’s overall performance and “sweet spot” size.

For example, the bat uses a finely tuned barrel profile to create more surface area for contact with the ball, resulting in faster exit speeds and farther hits according to It also incorporates a balanced swing weight and minimized vibration on contact to allow players to swing faster and control the bat better.

While Marucci argues these technologies make the Cat 5 an innovative advancement, many leagues view them as giving players using the Cat 5 an unfair boost in power and performance over standard bats. This perceived performance enhancement is a primary reason the bat has been banned from most youth baseball.


In summary, the Marucci Cat 5 baseball bat has been banned by most major baseball organizations due to performance and safety concerns. The bat was found to provide players with an unfair performance advantage over standard bats, with test results showing the Cat 5 had better bat exit speeds and allowed players to hit the ball significantly farther. There were also concerns over the bat’s durability and tendency to crack or break, posing a safety risk to players, catchers, and umpires.

While the Cat 5 became popular for its hot performance right out of the wrapper, the bat ultimately went too far in enhancing power hitting. With player safety as the top priority, baseball regulators determined the risk of the bat outweighing the performance benefits. The universal banning of the Cat 5 across high school, college, and professional levels shows the commitment to fair and safe play above all else.

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