“Baseball Myths”

August 16, 2007

Does a corked bat hit balls farther?

Adam and Jamie try to prove that a corked bat doesn’t give any advantage.


The corking process was not described, and there are many variables. For example, is the cork glued to the bat? Is it a solid piece of cork, or made of reconstituted cork? What density of cork? Is the cork used to plug the hole larger than the hole itself, like a Champagne cork? How is the endcap re-fitted on the bat? What is the depth and size of the hole drilled for the cork? They seem to have only tried one version, when there are many variables. Thus, their “corked bat” is almost certainly different than what the major league players are doing.

Adam used his own measurement for bat swinging speed, not that of a professional baseball player. Poor modeling.

Used “average” fastball speed, instead of what a real professional pitcher would throw. Poor modeling.

Was the corked bat lighter than the original? By how much? Lack of data collection.

Lighter bats lead to higher swing speed, which they explicitly stated as a problem with corked bats. Extremely poor modeling of swing physics.

Did the corked bat have different damping or “spring” than the full wood bat. Poor analysis.

Corked bats are known to have broken during real games under real conditions, so they should be able to reproduce this under normal circumstances to know if their bat has been properly corked.

My Verdict:

Analysis Totally Busted. Poor analysis, poor modeling of bat and ball speed and vague corking process make this very unconvincing.

What they should have done:

Built a rig that correctly spins a ball in flight.

Built a collection of differently corked bats and compared them.

Reproduced the known case of breaking a corked bat under ‘normal’ circumstances.

Can a baseball really slide and curve, or is it just an optical illusion?

High speed camera data is interesting. This isn’t really a “myth”, its just science.

My Verdict:

Analysis Confirmed.

Physics of a ball in flight.

Again, not actually a myth, just science content.

One thing to note is that the “scientist” says that a ball can’t rise in flight because its impossible to produce lift greater than the weight of the ball. This is true of a ball thrown perfectly level, but not necessarily true of a ball thrown upwards. One nit: NASA Ames Research Center isn’t in San Francisco (as stated), its in Mountain View.

My Verdict:

Analysis Confirmed.

Is a humid ball “harder to hit” (or does a dry ball go farther than a humid one)


Tori and Grant do a reasonable analysis here, with pretty good control data, and their data collection actually looks good. They did a good job including controls, and I especially like the inclusion of a “dry” ball. The biggest problem here is that they didn’t use an actual cigar humidor, which may not have the same humidity as their rig did.

The biggest flaw with this analysis is that humid balls contain more water, and thus, will weigh more. Their data says that the humid balls bounce 14% less high — do they weigh 14% more? That would lead to similar results for a totally different reason.

Are the balls really humid enough? How do they know when the humidity has reached the center of the balls? There should have been more testing here, with slicing humid balls to measure their core humidity.

My Verdict:

Analysis Plausible, but they didn’t answer the original question. Are humid balls “harder to hit”? Doesn’t that mean that humid balls would lead to more fouls or strikes than dry balls? Clearly, humid balls don’t fly as far, but the reason behind it is unclear. Is it due to humidity in the hide, increased water weight, or reduced spring in the core of the ball?

What they should have done:

Weighed all the balls and made sure that weight was not a factor.  They could have even calibrated humid and dry balls to the same weight to see if its the humidity or the weight that causes the balls to be hit farther.

Does sliding in to base slow you down, or speed you up?

Tori, Grant and Keri demonstrate themselves the difference between sliding and running.


None of them had ever learned to slide before. They had just learned, so they were no where even close to a professional level of slididng.

They were also not professional level baseball players, who train for base running technique on a regular basis. Maybe a professional player can stop or run faster (without sliding) than they can.

My Verdict:

Analysis Plausible. Clearly amateur baseball players can slide faster than they can run, but what about professionals?

What they should have done:

The exact same thing, but with professional or even amateur baseball players.

Can you hit a ball so hard that the hide comes clean off?

Adam and Jamie try to produce a rig that will hit a ball so hard that the hide comes off.


Balls were sent towards a static bat on a loose mount. This is very poor model of the bat/ball interaction. With 90mph fast balls, and bat swings at approximately the same speed, modeling the relative velocity of the bat and ball at 200mph is a reasonable starting point. Their 400mph number (with a static bat) is only 2 times faster than “normal”.

Balls coming out of their air powered rig have no spin. This is a very poor model of a real baseball in flight.

Balls most likely to have their hide fall off are “old” balls, or balls that have manufacturing flaws, or have been hit a few times already. This was not modeled.

The scenario most likely to remove the hide is where the seam of the ball strikes the bat at a very steep angle, producing the maximum shear force on the stitches. This was not modeled.

I assumed that there are recorded occurrences of this happening. Are there? Did they research it?

My Verdict:

Analysis Busted. I don’t think they adequately modeled the interaction between bat and ball, and the rare circumstance that would lead to the hide coming.

What they should have done:

Properly modeled the bat/ball interaction with spinning balls and moving bats.

Tested some scuffed and old used balls.

Made sure that the balls hit the bat at various oblique angles for maximum friction between ball and bat.


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August 15, 2007

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