On the night of Sept. 27, at the Phillies-Nationals game at Citizens Bank Park, my wife's face was split open by a baseball off the bat of Odubel Herrera. We were seated in Section 116, Row 10, behind the protective netting on the Phillies dugout — but the ball arced over the eight-foot-high barrier and zeroed in on her at an astonishing rate of speed.

The tip of her nose was split open down to the cartilage inside her nostril, and the cartilage was fractured. The impact burst her lip below the nose through to her gums. Over the next 12 hours, her lips, checks and eyes turned purple, and her sinuses filled with blood. Her voice became distorted by the swelling and sinus congestion. A CT scan of her face revealed that her nasal passage was completely blocked by swelling. A masterful plastic surgeon put her nose and mouth back together, and she'll need dental repair for chipped teeth.

That such a serious injury could happen despite the protective netting seems improbable at first glance. But it illustrates how little is known about the epidemiology of ballpark injuries from thrown or batted balls. On that night, 10 of Major League Baseball's 30 teams had responded to Commissioner Rob Manfred's 2015 recommendation that all teams consider extending protective netting, which protects spectators from the force of balls flying at speeds in excess of 100 mph. On Sunday, the Yankees became the 11th team to take this step, after a horrific injury to a small child on Sept. 20.

The Phillies immediately took my wife to their first-aid room, where she was attended by a physician and other staff. Based on the questions we were asked and the information available about the incident, Major League Baseball has the wherewithal to understand the who, the what, the where, the why, and the how of all ballpark injuries like the one my wife sustained. Taken together from all ballpark injuries of this kind — a 2014 Bloomberg analysis found that 1,750 people are hurt by foul balls at MLB games each year — these data points are a crucial trove of information to protect fans.

Although very little information is publicly available about the epidemiology of such injuries, comments by baseball executives suggest that facts about the risk of injury are well known by the teams. The Jacobson family in New York, in classic blame-the-victim style, has been criticized for bringing a small child to a seating area so close to the playing field on Sept. 20. Baseball's "assumption of risk doctrine" has shielded teams from the consequences of the risk at which they place fans.

The question should not be why the injured didn't protect themselves, but why such unsafe ballpark conditions are allowed to persist. As I was reminded, to my sorrow, nonprofessionals are defenseless against a batted ball sent into the stands by some of our nation's top athletes. I saw the ball coming, but could not react in time to protect my wife — just as the grandfather in New York City was unable to protect the toddler tucked next to him in the stands last month.

The discourse these injuries have generated has been remarkably shallow and self-serving. Defenders of the "no net" policy say this step is deleterious to the fan experience and the value of tickets so close to the field. In fact, seated behind the net that night, we barely noticed it was there. The fine fiber nets that are used today are barely noticeable and blend into the dark background of the field and the night. And the most expensive seats in the park, behind home plate, have always been protected with netting.

What are the facts that argue for the placement of nets? How high should they be? How far should they extend down the dugout or beyond? What other injury prevention measures should be deployed?

There are no publicly available facts beyond the periodic news reports of these occurrences. My review of the injury prevention literature yielded one Japanese study that identified the reasons that first aid is sought in a ballpark. The U.S. Centers for Disease Control and Prevention Injury Prevention Branch has not published on the subject. It should come as no surprise that in the Japanese study, injuries from balls and bats entering the bleachers were at the top of the list of ballpark injuries. Aside from being in attendance at a ball game, there was no information on risk factors.

Much more data could be gathered and analyzed to develop functional strategies to protect fans. The teams know the seat location of every injured spectator. The first-aid staff can provide information on the type and severity of injuries. From attendance figures and ticket use data, the rate and frequency of injuries can be determined. Day games vs. night games, the age and gender of spectators involved, game data to identify the role of batter-pitcher matchups, and the type and speed of the pitch may all be useful in providing a more complete analysis of these events.

A sports business that is now so rich in metrics that it can report on the exit velocity of every batted ball can surely identify the factors associated with spectator injuries. If the magnitude and severity of the injury problem were known, solutions might be more compelling and evident — and provide the necessary call to action. Without such information, every decision about fan protection is speculative — and spectators will continue to be imperiled at each game.

More than a week after that night at the Phillies game, the swelling and discoloration of my wife's face are finally receding, and we hope there will be no lasting effects. But it's time for every team to update its preventive measures based on available evidence and protect its fans. The assumption-of-risk doctrine should not be a license to ignore a common harm.

PJ Brennan, M.D., is the chief medical officer of the University of Pennsylvania Health System. PJ.Brennan@uphs.upenn.edu