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September 18, 2015

The PSI Numbers Behind Deflategate

-- Saying hello to our old friend PVnRT

Just in case you wanted to know the numbers because heaven forbid in a story that generated 9 months of writ, invoked an independent investigation, required intervention from a federal judge, incurred an estimated $15 million in attorney fees and bodyslammed the reputation of two of the NFL's most powerful, anyone would want to know the actual numbers.

What numbers in particular? The only ones that matter: pounds per square inch. Here are the bare bones you need to know about Deflategate, presented as simply as I can muster.

Fact #1 - The league requires footballs to be inflated within 12.5 to 13.5 PSI.11. What type of league allows for variance in their primary equipment is beyond me. Can you imagine MLB allowing pitchers to customize the weight and size of their baseballs?

Fact #2 - Each team in a NFL contest prepares their own balls pre-game and uses their balls when on offense. Different teams hold different preferences regarding the level of ball inflation. Some teams prefer a hard ball, and consequently target an inflation level of 13.5 before the game. Others prefer a softer version.

Fact #3 - While inspecting the Patriots balls pre-game, the designated official found the balls to be slightly below 12.5 PSI. He inflated them to 12.5, verifying such with a gauge.

Fact #4 - At halftime, under suspicion of ball tampering, officials using two different gauges measured 11 of the 12 Patriot footballs. The results of the two gauges varied significantly: one gauge returned a higher PSI, while the other returned a lower PSI. (see chart below, taken directly from the Wells Report. The gauge designated 'Prioleau' was the higher measuring gauge while the 'Blakeman' gauge was the lower measuring)

Fact #5 - The higher gauge returned PSI values from .30 to .45 higher than the lower gauge.

Fact #6 - The average PSI of the balls using the higher gauge was 11.49. The average PSI of the balls using the lower gauge was 11.11. Both of these figures are below the 12.5 minimum. If this game had been played in a vacuum, in a world where air doesn't escape from balls due to low temperatures or from being crushed under 250- to 350-pound humans, it would appear that at some point between the initial officials' measurement and the end of the first half, air had purposely been removed from the Patriot footballs.

Fact #7 - The game was not played in a vacuum.

Fact #8 - According to the Ideal Gas Law,22. Pv=nrt, aka, pivnert, one of the few physic equations I actually remember. Sorry Gene. footballs exposed to the weather conditions prevalent on the date of the Patriots-Colts game would be expected to lose between .98 and 1.18 PSI during the course of one half of play. This would mean that a ball originally properly inflated to 12.5 PSI would measure at halftime between 11.32 and 11.52 PSI.

Fact #8 - Aka, fact #6 again. The average PSI level of the balls using the higher guage was 11.49, which falls directly between the expected values per the Ideal Gas Law. The average PSI level of the balls using the lower gauge was 11.11, which is below the range predicted by the Gas Law, thereby suggesting that air may have been manually removed from the balls at some point.

(Please allow a break in the listing of facts for what should at this point be an obvious question)

Question: So which gauge did the official use when he measured the Patriot balls at the beginning of the game? And why does it matter? Because you can't do a science experiment with two instruments of measure that return varying results! It comes down to this: if the official used the high measuring gauge at the start of the game, then the balls experienced a net drop in PSI of 1.01 pounds which would be exactly in line with expectations set by the Ideal Gas Law. If the official used the low gauge at the beginning of the game, then the balls experienced a net decrease of 1.39 PSI, a drop exceeding the one predicted by the Gas Law, suggesting tampering of some sort caused the extra ball deflation.

(Facts resume)

Fact # 8 - The official in charge of measuring the balls during pre-game, one Walt Anderson, was interviewed during the NFL's independent investigation and asked which gauge he used pre-game. His "best recollection" was that he used the higher gauge. (Note that the gauges were not identical; they each had distinguishing features. The higher gauge had a Wilson logo on it and had a long, crooked needle. The gauge that measured low had no logo and had a shorter, straight needle.)

Fact #9 - The NFL leaked a report to ESPN that 11 of the 12 Patriot footballs were underinflated, ignoring the potential impact of weather on PSI and completely dismissing the head official's assertion that the higher gauge -- the gauge showing no tampering occurred -- was the instrument used in the data collection. They then relied on these fifty-fifty findings to levy a suspension on Tom Brady that was double the severity of the one originally placed upon a guy that was caught on tape knocking out his wife in an elevator.

And you're surprised that Brady's suspension got overturned, why exactly?

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