Experts are weighing in on “Deflategate,” the name the media have bestowed upon the allegedly conspiratorial events that resulted in Tom Brady’s four game suspension from the NFL. The initial investigation of underinflated footballs relied heavily on expert opinions. Brady also relied on an expert when he appealed his suspension to NFL Commissioner Roger Goodell.

A federal court lifted the suspension for reasons that were largely unrelated to the expert testimony. That ruling is now on appeal.

Deflategate Investigation

The New England Patriots battled against the Indianapolis Colts for the right to advance to the 2015 Superbowl. According to an investigative report “concerning footballs used during the AFC championship game,” the Colts questioned the inflation levels of the footballs the Patriots were using during the first half of the game. An NFL rule requires footballs to be inflated to a pressure within the range of 12.5 to 13.5 psi during league games.

At halftime, the officiating crew tested the balls that had been used by both the Patriots and the Colts. The officials found that all of the Patriots’ footballs were underinflated. The footballs supplied by the Colts were within the accepted range, at least according to one of the two pressure gauges that were used to test them.

The report concluded that a locker room attendant and an assistant equipment manager employed by the Patriots participated in a scheme to deliberately circumvent the NFL rules by releasing air from the footballs after they were examined by the officiating crew. The report also concluded that Brady was “generally aware” of their inappropriate activities.

Experts Analyze Football Inflation

The investigative report relied in part upon the input of experts, including Dr. Daniel Marlowe, a professor of physics at Princeton, who coordinated testing and analysis provided by an engineering firm. The experts determined that a reduction of air pressure in a football between the start of the game and halftime is a natural result of footballs moving from warm locker rooms to chilly playing fields. The experts nevertheless determined that the drop in air pressure within the Patriots’ footballs was greater than the laws of physics could explain without the intervention of someone releasing air from the balls. The experts also concluded that a deliberate release of air was the only credible explanation for the greater reduction of air pressure in the footballs used by the Patriots than those used by the Colts.

The experts examined and ruled out a number of alternative explanations for the pressure drop, including natural leakage, the repeated insertion of inflation needles, defects in the gauges the officials used to measure pressure, the relative humidity in the rooms where the balls were stored, and rough handling of footballs during the game. In particular, the experts discounted the explanation offered by Patriots’ Coach Bill Belichick, who claimed during a press conference that the vigorous rubbing of footballs in preparation for the game accounted for their loss of pressure.

The investigation was based on interviews and a variety of evidence, including text messages between the locker room attendant and the assistant equipment manager discussing Brady’s displeasure with the degree to which footballs are inflated. The locker room manager called himself “the deflator” in one of the texts while other texts refer to an inflation needle that the assistant equipment manager said he would provide to the locker room manager. A video showing the locker room manager carrying a bag of footballs into a bathroom before he carried them onto the field was particularly decisive evidence. The expert evidence nevertheless contributed substantially to the investigative results by ruling out innocent explanations for the discovery that the footballs used by the Patriots were underinflated during the first half of the championship game.

Brady’s involvement was suggested by his gift to the locker room manager of an autographed jersey and two autographed footballs during the week before the championship game. The text messages also suggest that Brady knew of the plan to deflate the footballs. The suspicious timing of telephone calls between Brady and the assistant equipment manager immediately after concerns were raised about the football inflation level also contributed to the conclusion that Brady was at least generally aware of the plan to deflate the footballs. The report did not find sufficient evidence to accuse Brady of directly participating in the deflation conspiracy.

Expert Helps Brady’s Challenge

The NFL imposed a four game suspension on Brady. Brady appealed to NFL Commissioner Roger Goodell. At the appeal hearing, Brady testified that he knew nothing about a scheme to deflate footballs. He was unable to explain, however, what happened to the cellphone that he used on the day of the championship game. He said it was “missing” when the investigators asked to inspect text messages on that phone.

The player’s union, on Brady’s behalf, called Edward Snyder, a professor of economics and Dean of the Yale School of Management, as an expert witness. Snyder challenged the findings of Marlowe’s team. Snyder testified that Marlowe failed to factor timing into his analysis of the different pressure drops. The amount of time each ball spent in a warm locker room after being carried in from a cold field would affect the ball’s pressure. The Colts’ footballs were inspected after the Patriots’ footballs, and that reason alone would account for the Colts’ balls having higher pressure, but Snyder believed that Marlowe’s team did not account for the timing differences.

Two gauges were used to measure pressure at halftime and, since they consistently showed different results, Marlowe’s team applied an adjustment to account for the difference. Snyder faulted Marlowe’s team for failing to apply that same adjustment to the gauge used to measure ball pressure before the game started. Snyder concluded that had they done so, the pressure level in eight of the Patriots’ footballs would have been at an acceptable level.

Although Snyders’ interpretation of Marlowe’s test results was challenged on cross-examination, other experts have recently criticized the methodology used by Marlowe’s team. In the end, it is likely that Goodell placed more weight on text messages and video evidence than he placed on the scientific analysis. Goodell upheld the suspension.

Brady’s Court Case

Brady successfully challenged his suspension in federal district court. The court ruled that the NFL gave Brady no notice that “general awareness” of tampering with footballs or a failure to cooperate with the ensuing investigation would result in a suspension from play. The court also noted that the NFL violated Brady’s procedural rights by denying him access to evidence prior to his appeal hearing.

The NFL appealed and Brady’s case is now before a federal court of appeals. At this point, quarrels about expert opinions are less relevant than Brady’s contention that the NFL did not treat him fairly and that it failed to follow its own rules by imposing a four game suspension, rather than a fine, for his “general awareness” of football tampering.