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Bat rules explained

"BBCOR", "BESR", "MOI", "ABI", "Drop" - what in the world do these mean and what do they have to do with a baseball bat? Well, as it turns out, quite a lot. Years ago, bat manufacturers, in the interest of providing a competitive advantage (and to sell more bats), developed models with materials other than wood such as aluminum and other metal alloys. As the years went by the science of these materials and the designs of the bats became much more sophisticated, again, all in the name of providing hitters with an advantage at the plate, and it worked: batting averages and offensive numbers increased noticeably at all levels where non-wood bats were permitted.

Things reached a peak when bat makers began offering exotic composite materials in the barrels and/or handles of the bats, creating even higher performance numbers and competitive advantages. These bats were also extremely expensive and subject to cracking and even shattering, plus, as it turns out, they posed a safety hazard to defensive players because of the increased speed of the ball coming off the bat.

The exaggerated offensive performance figures, combined with the safety concerns and illegal practices such as bat-doctoring, prompted officials of the game, from the college level and down, to begin considering restrictions in the use of non-wood bats. (Some purists would like only wood bats to be used like they are in Major League Baseball, but that wasn't about to happen.) The goal was to come up with standards for non-wood bats that made them perform like wood bats, even if it meant reducing offensive performance numbers, and at the same time reduce safety concerns.

The process took some years and went through various phases of implementation, but in 2012 it all came together. New non-wood bat standards have now been implemented by the NCAA, the National  Federation of High Schools (NFHS), Little League International, and other youth baseball organizations.

For those who want to know the technical details of how and why these standards were developed, keep reading after the next section. For those who just want to know what bats can and can't be used, let's cut to the chase -

The following are guidelines for bats to be used at Lakeland City Baseball games:

For Major League and below -

  • All bats must not exceed a maximum diameter of 2-1/4".
  • Any bat that does not have composite materials in the barrel (i.e., all metal, all alloy, all wood) and meets all other applicable standards is permitted. Remember: wood bats are permitted in Major League and below as long as they do not exceed 2-1/4" in diameter.
  • Any bat with a handle made of composite materials and with a barrel of non-composite materials (i.e., alloy), and meets all other applicable standards and maximum diameter is permitted.
  • No bat with a composite barrel is permitted for use except those listed on the Little League International list of approved composite-barrel bats, which can be found by clicking here.

For Junior League -

  • All bats must not exceed a maximum diameter of 2-5/8".
  • Any bat that does not have composite materials in the barrel (i.e., all metal, all alloy, all wood) and meets all other applicable standards is permitted. Remember: wood bats are permitted in Junior League as long as they do not exceed 2-5/8" in diameter.
  • Any bat with a handle made of composite materials and with a barrel of non-composite materials (i.e., alloy), and meets all other applicable standards and maximum diameter is permitted.
  • Bats without composite materials in the barrel can have any "drop".
  • Bats with composite barrels are permitted in Junior League but must meet the "BBCOR .50" standard and be permanently labeled so.

(Note: Lakeland City Baseball is not an organization chartered by Little League International, but we do follow many of their guidelines for bat use.)

The Geeky Stuff

As explained above, non-wood bats became way too "hot", meaning they were performing at levels much higher than wood bats, to the point where it could be said that it was more the piece of equipment generating the high batting numbers and less the human attached to the other end. Plus, people were getting hurt.

So what does a non-wood bat do differently than a wood bat? Well, the main reason non-wood (metal) bats were developed was to make the ball go further, faster. How do you measure that? One way is to use a measurement called "batted-ball speed", or BBS. When compared with a wood bat, bats using different materials in the barrel could generate a higher BBS, making them VERY attractive to hitters looking for an advantage.

When it became evident that metal bats were going to become the norm at the college and high school levels, and they were outperforming wood bats by a wide margin, the NCAA decided to come up with a bat performance standard so they could begin controlling their use, because without some sort of limit bat manufacturers were going to keep developing higher-performing bats and further distort the game. The new standard of that day was called the "Ball Exit Speed Ratio", or BESR. It is a formula that produces a ratio of the speed at which the ball exits the bat/ball collision divided by the combined speeds of the bat and ball before the collision.

By knowing the BESR of a bat, comparisons could be made between the various types of bats, therefore limits could be placed. The limits were achieved by regulating something called the "Moment-of-Inertia", or MOI. The MOI directly affects the bat swing speed, meaning that a bat with a larger MOI would be more difficult to swing. Lower bat speed due to a larger MOI means a lower BBS, which means a lower BESR. A smaller MOI would result in the opposite. The MOI is regulated by adjusting where the weight is in the bat: The bulk of the weight near the handle makes bats swing faster, whereas more weight in the barrel makes them slower.

Bat doctoring, "aging" and ABI
There was an initial dampening effect on bat peformance when the BESR was regulated, but manufacturers quickly found ways around it, particulary with the advent of composites. These high-tech resin and adhesive materials produced bat barrels with a bouncy, or "trampoline" effect when coming into contact with the pitched ball, adding yet another performance factor to non-wood bats. With the advent of composites, some wiley users discovered that by running the composite bat's barrel through nylon or hard-rubber rollers, or by compressing or hammering the barrel, they could break down the resin and adhesive layers and accelerate the "aging" of the bat, and an aged composite bat becomes more flexible, or springier, enhancing the trampoline effect, therefore creating a higher ball speed off the bat. These "bat doctoring" techniques are now considered cheating. Artificially "aged" bats crack under impact with a pitched ball and even shatter into pieces, putting defensive players at risk and costing the players and/or parents a LOT of money to replace the bat. (Then there was a cat-and-mouse game being played between the bat owners and manufacturers about what was and wasn't covered by the warranty, something very important to people dropping hundreds of dollars on a bat.) Part of the new standards include ABI, or accelerated break-in, guidelines. The ABI standard establishes how a composite-barrelled bat must perform during its potential useful life in the field, with the goal of having the bat stay at or below a certain threshold of performance during its natural, and unaltered, lifetime. Any increase in performance after the bat's production is not allowed.

Cheaters, beware.

Welcome BBCOR
To get a handle on these new composite-barrel bats for use in Junior League, a new testing protocol was developed called "Bat-Ball Coefficient of Restitution", or BBCOR (pronounced "bee-bee core"), which, when combined with the BESR, MOI and ABI standards, are the overall measures bats with composite barrels must achieve to be used in LCB Junior League games and elsewhere. BBCOR standards are designed to compare performance versus wood bats, and with limits intended to make composite-barrel bats perform like wood bats.

Simply put, the BBCOR standard sets the maximum trampoline effect a bat can have over its natural and unaltered lifetime in the field. Think of a tennis ball being hit off a tennis racket versus bouncing it on the floor. The tennis ball will travel much further off a racket than off the floor. The racket strings deflect, or bend, then jump back and propel the ball. The floor won't bend, thus the tennis ball won't travel as far. That is the same effect of a baseball struck off a hollow bat versus a wood bat. The hollow bat surface of a composite barrel will deflect significantly when coming into contact with the baseball, then spring back, providing more energy and a higher speed off the bat to the ball, whereas a metal bat will deflect only somewhat and a wood bat hardly at all, almost eliminating the trampoline effect. If you limit the trampoline effect you limit the speed of the ball off the bat.

BBCOR makes composite-barrelled bats perform like wood bats.

Get the drop
It so happens that the BBCOR standard also limits the "drop" of the bat. ("Bat drop" is the difference between a bat's length and its weight. A 30" length bat weighing 25 ounces will have a -5 bat drop.) All BBCOR-labeled bats will automatically have a drop of -3 or less.

Wither wood?
The goal with the BBCOR standard was to produce a speed off the bat and other performance measures as close as possible to those of the best wood bats. That goal was achieved when a bat measured a coefficient of 0.500 using the BBCOR formula, hence the term "BBCOR .50", which is what you'll see on the new bat labels.

The bottom line
What is the effect of the new standard? It is agreed that at the NCAA and high school levels there is a measureable 5-6% decrease in bat performance, and a noticeable difference in the sound of the ball striking the bat. It is more of a thud and less of a ping. Batters at those levels lament the loss of the advantage 'hot' bats had given them, but the result is that batted balls will not travel as fast, or as far; there are fewer home runs; defensive players are safer and we'll all get back to emphasizing the fundamentals with a more balanced game. It's almost like everyone's gone to a wood-bat league...

Going, going... gone!
'Juiced' composite bats are history. Advantage: pitchers and good defense. Small ball is back!


- OR -

HOWEVER, unlike high school, LCB Junior League players can use a non-BBCOR bat, but they cannot have a composite barrel. Bats with aluminum or alloy barrels are permitted whether they have the BBCOR label or not, and of course, wood bats are permitted as well. All bats in LCB Junior League must not exceed a 2-5/8" barrel diameter.