Updated: July 3, 2020

Back to the BESR

By Jon Zayle and Brian Duryea

What are BESR Bats?

BESR was the baseball bat certification requirement for NCAA and high school baseball play between 1998 and 2011.

Short History – BESR was implemented in 1998 to address non-wood bat performance. Through the early 2000’s under the BESR standard, bat companies perfected bats to pass the test but perform above it after the bat were worked in. By 2010 the NCAA banned all composite BESR bats after finding a considerable amount of them exceeded performance standards in play. For 2011 they implemented a new standard called BBCOR.

Safety Test not Performance Test

We are currently immersed in a world of BBCOR, USA and U Trip bats. Proceeding each of those was a standard called BESR. Each of the tests associated with those bats certifications are better understood in terms of a safety test NOT a performance test. Too many, we think, confuse a high score on a certification test the same as overall bat performance.

Granted, all the tests measure exit speeds in some fashion but none measure even most given conditions during field play. In fact, each of them only measure a single (pitch + exit) speed. BBCOR, as an example, uses only 136mph. The tests intend, and we think accomplish, a control for the safety of ball flight given a common impact condition. But they don’t restrict or measure performance at any other bat and ball speed conditions–which are many and varried. Hence the reason theses tests are better understood as safety tests not performance tests.

We take a look at all three major tests (BESR, BBCOR/USA and USSSA) and what they mean.


BESR, or Ball Exit Speed Ratio, could simply be called “pre-BBCOR,” but that would both offend physicists and bat nerds alike. For now, keep that thought as we take a walk down memory lane.

BESR Royalty

2010-11 Easton Stealth

If you can find one of these in decent shape for less than a second mortgage we say go for it. Granted, you won’t be able to use it in any NCAA/NFHS games, but it can rake once worked in. The Easton Stealth, along with a few other composite BESR bats, are the reason these things got banned.

BESR Than Average


2010 Slugger TPX Omaha

As popular then as it is now, Slugger’s TPX Omaha ruled the dance in the BESR bat space circa 2010. It’s feel was crazy stiff. As a single piece aluminum it didn’t have quite the bomb dropping work in as others in the class, but it was a well priced work horse.

BESR OG Royalty


2009 Easton Stealth IMX

If there were a Mount Rushmore of BESR bats the 2009 Stealth IMX would be on it. This is the same bat Mike Trout used in High School so you know it must be good. If you play in a league that doesn’t have any rules this is a legit one to get.

NCAA Bat Restriction History

From 1970-1973, the NCAA used wood bats in competition. What a crazy idea. In 1974, that changed with the use of aluminum. Until 1986, there was no weight limit on NCAA bats. Insane.

In 1986, a -5 rule was created, about the same time that the Easton Black Magic was released. Ponder that for a moment. A stud college hitter using a drop 5.

USC defeated Arizona State 21-14 that year in the CWS. That’s a lot of touchdowns for a baseball game.

After the 1998 season, the NCAA realized things were a bit crazy when pretty much every record was broken, and in August 1999, it adopted BESR to regulate the performance of composite and aluminum bats. This reduced the barrel size to 2.5” and mandated a -3 drop.

See the history of college baseball bat performance.

This rule change did not solve every issue, especially at the youth level, as a few reported deaths occurred in the U.S. According to the Sports Science Laboratory at Washington State University, BESR differs from BBCOR, such that BESR was concerned with the exit speed of a non-wood bat and focused on length, as compared to BBCOR, which focused on a wood bat standard.

“BBCOR” means Batted Ball Coefficient of Restitution. Bust that out at your next team meeting for extra credit.

Calculating BESR

BESR’s calculation is not uncomplicated. You can read in depth how it works here. In short, it’s measurement is as simple as its acronym: Ball Exit Speed Ratio. That is, the ratio associated with the speed of the bat, speed of the ball and how fast the ball exits the bat. That ratio must be under a certain limit depending on the length and swing weight of the bat to pass.

Although the physics is solid, BESR failed as a standard mostly because the test did not work composite bats in before they tested. Manufacturers began building bats that would pass the test out of the wrapper. But, once worked in, would exceed the test standard. Hence the reason the BESR standard is now defunct.



Both BESR and BBCOR are safety performance tests. They differ in some serious ways—the most important being that BBCOR bats are worked in before they are tested.

Calculating BBCOR

BBCOR is in reference to a safety performance test, implemented in 2011, of NCAA approved baseball bats. Specifically, BBCOR is in reference to how elastic a stationary bat is when colliding with a ball traveling 136 mph. As the collision occurs, a bat which compresses more easily makes the baseball compress less. Less compression in the baseball means it retains more of its energy. More energy in a baseball means higher exit speeds. So a bat that compresses more easily will create a ball exit speed with higher velocity. (Hence the value of compression tests on bats). The more a bat compresses at collision with a ball the higher the BBCOR. For example, 1.000 describes a bat that takes on the full elasticity of the collision which keeps maximum energy in the ball.

(In practice, a 1.000 COR is impossible as some of the energy is lost in heat (kinetically) at impact. So, in a wildly ironic twist of bat jargon, a bat getting “hot” at impact actually does the opposite as to what the word ‘hot’ means in bat circles. What we really want is some chemical reaction in the bat that makes it freeze at impact and deliver even more energy into the ball. Maybe the 2088 DeMarini CFZ Review? But ‘that bat is so cold’ doesn’t have the same ring to it. See this Wikipedia article on COR).

BBCOR standards require bats have no greater than a .5000 BBCOR score. Meaning, at least in my tiny brain, a bat cannot take any more elasticity than the ball does. (If 1.000 is 100% than .50 must mean half that, right?) The reason the NCAA chooses .500 BBCOR is to most closely replicate the natural coefficient of restitution (BBCOR) of hard wood bats.

Interestingly, the COR of the bat and ball collision isn’t proven by visually measuring the compression of the ball and bat at impact. Instead, the number is calculated by some rather mind bending formulas with exit speeds, ball cannons and radar guns you can read about here.


BPF is determined differently than BBCOR but has the same intent as a safety performance test. It is calculated by taking the ratio of a ball’s exit speed bouncing off a bat compared to the speed of the ball when bouncing off a brick-wall. USSSA allows the ball/bat bounce to be no greater than 15% faster than that of the ball/brick-wall bounce. This is represented as a 1.15 BPF rating. Or, said differently, a stationary BPF 1.15 bat will bounce a ball no grater than 15% faster than that same ball getting bounced off a brick wall (at the same speed).

In practice they don’t actually shoot a baseball off a brick wall. They already know those numbers. Instead, they need to measure the exit speed of a stationary bat getting hit with a baseball. Like BBCOR, BPF 1.15 bats are worked in before the test.

What is a .500 BBCOR rating in BPF?

Of note, a BBCOR bat has a BPF rating of 1.00—which is modeled after the natural trampoline effect found in hard wood bats—which turns out to be about the same as a brick wall. If you’re into math, and any of that made sense above, then this formula will help:

BPF = (BBCOR/COR of the Ball)

If you’re dead serious about understanding how this all works then dive in here.


Do you remember the Orange Easton Stealth CNT? Some of you might, and some of you might have the fractures to prove it. LSU destroyed the ball with that bat, hitting over 100 HRs in one season. You will still see some -10 Stealths floating around Cooperstown (though I have heard the -3 version is banned at ASV, even though it is not listed in the banned list of bats specifically).

Rumor has it ASV had to reinforce that rule this past summer.

The last year of BESR resulted a national batting average of .305, 6.98 runs per game and .94 HRs per game.

A 2009 NCAA press release admitted that 20 of the 25 bats tested at the CWS failed BESR testing; that is, they were on FIRE and launched missiles over 100mph off the bat. New technology and better materials created a new breed of weapons for NCAA and High School use. Titanium bats. Really? One bat by Slugger had an air bladder that compressed on impact. Totally insane. The trampoline effect was out of control.

Composite bats were then banned in 2009 from NCAA play while they figured things out.

(See if BBCOR Bats ruined college baseball)

We all know what happened next. The NCAA and NFHS mandated the use of “BBCOR” bats in January 2011, and as expected, runs and offense took a nose dive. Besides the bat manufacturers that get to sell new bats, it has been posited that MLB was also a winner because a club could evaluate hitters earlier given the wood bat standard, instead of trying to extrapolate stats from a hitter using a firestick.

I love a good conspiracy theory, and the more we get into bats, the more we will find.

I would be remiss if I didn’t mention everyone’s new favorite bat term, “integrity.” Integrity is used in the USA Bat standard as a basis for the youth standard change, but has yet to be defined. As we know, the move to the USA Bat standard had nothing to do with safety, per USA Bat’s FAQs.

What if I told you that the move away from BESR was put in place specifically to address the safety concerns of batted ball speeds of certain composite and aluminum bats that were severely outperforming their BESR rating, and that the solution was to have a bat conform to a wood-like bat standard?

I can’t recall where I heard that before, but I feel like every 7 years someone is going to make a ton of money selling new bats that lessen the trampoline effect.