Sports Science of Baby and Dad at Wrigley, Batted Ball Exit Velocity, and What it Means for Infants

Tuesday, June 23, 2015 Chicago Cubs fan Keith Hartley caught a foul ball pop fly while holding his infant son during the second inning of Tuesday’s game at Wrigley Field. Hartley and the catch became the subject of news media frenzy and a social media surge.

Hartley was sitting in a box seat with his wife and son down the first base line when Cubs pitcher Jason Hammel hit a pop fly toward him and his 7-month-old son, Isaac. Dad caught the ball with his bare right hand just above the mitt of Dodgers first baseman Adrian Gonzalez. Instantly public opinion was divided by those who thought Hartley shouldn’t have put his infant at risk, and by those who thought the catch and multi-tasking was awesome. Anti-Hartleys commented that the ballpark — especially the box seats section — is no place for an infant, period. Pro-Hartleys proclaimed Hartley as a hero — a multi-tasking Dad who protected his son by catching the ball before it had the chance to ricochet around the box seats. The pro-Hartleys honored his athletic prowess and ability to make a great barehanded catch, but ignored the fact that Hartley made a considerable reach to catch the ball just above the first baseman’s mitt. In the given 5 seconds, Hartley failed to assess that the ball — falling at about 52 MPH with about 90 LBS of force — would have been caught by Gonzalez or would have dropped between the rolled tarp and the box seats wall. As ESPN Sports Science contributor John Brenkus described, “in the 5 seconds that the ball was airborne, Hartley could have kept his baby safe, and potentially kept the inning alive, if he had done absolutely nothing.”

While most media stories promoted the catch in a positive light, Hartley found himself defending his actions in questions about social media comments that criticized his actions.

In a Chicago Tribune article Hartley said, “… baseball is not a new thing to me, I didn’t want (the ball) to hit the ledge and hit (first baseman Adrian Gonzalez). I wanted to make first contact, I think.”

Keith’s wife, Kari Hartley admitted she was “a little bit nervous” when she saw what was unfolding. But later in a MyFoxChicago interview she said “to be perfectly honest as it was coming towards him, I just thought ‘oh my goodness he needs to catch this ball, otherwise Isaac’s in trouble.’ I was thankful that he caught it … I didn’t have any question whatsoever that he could do it.”

Also in the Chicago Tribune article Hartley said, “I’m just trying to protect him (Isaac) first,” Hartley said. “We have the seating configuration so my two friends were closer to the ball if a sharp foul ball came. We’d all kind of stand up and make a wall.”

But if you look at the video of the play, Keith Hartley is closest to home plate in his group. In the next section, closer to home plate, two people are sitting behind a table with two Apple Mac notebook computers, which would prevent them from moving forward to form a wall to protect Isaac. They are hardly prepared to “stand up and make a wall” to protect Isaac from a sharp foul ball.

The surprising risk Chicagoan Keith Hartley took Tuesday night at Wrigley Field wasn’t just in his standing up and reaching out to grab a foul ball with one arm while balancing his infant son with the other arm.

It was also having the little guy in the first row midway down the right field line, where there would be nothing between his family and a screaming foul ball.

Sitting in any of Wrigley Field’s low rows, which are deliciously close to the field, demands a commitment to pay full attention to the action at all times.

— Philip Hersh (Chicago Tribune Good catch, bad decision?)

Just how much time do you think the group has to react to form a protective wall to protect infant Isaac from a line shot foul ball? Well, you know it’s less than 5 seconds. It’s actually about 0.93 second or 93/100 of a second — or less.

There’s actually a database available on the Internet that compiles MLB statistics and publishes the Batted Ball Exit Velocity for every major league player. A graph is available that shows the Average Exit Velocity By Week for Jason Hammel. His top Batted Ball Exit Velocity so far in the 2015 season is 92.8 MPH (once in the week of June 6 and once in the week of June 15 — June 23’s week wasn’t available yet). Better hitters have higher Exit Velocity stats. Hammel’s Exit Velocity is above the league average of about 88 MPH. The Dodgers leading home run hitter, Joc Pederson, has a top Exit Velocity of 102.4 MPH for the season, and has mostly been around the 93 MPH mark.

So what does this mean? Keith Hartley was sitting about 127 feet from home plate in the box seats section along first base — a section which actually projects into the field more than other sections. At Jason Hammel’s top Exit Velocity, a foul line shot into Keith Hartley’s seat would travel at about 92.8 MPH or 136.1 feet per second. Remember Hartley’s seat was about 127 feet from home plate. A ball traveling 136.1 feet per second takes 0.93 second to travel from home plate to Hartley’s seat.

How quickly can Hartley react to that line shot? Let’s examine what we know about pitchers and batters.

A 90 mph fastball reaches home plate in about 400 milliseconds or 0.4 seconds.

A batter has about 0.25 second to decide whether to swing or not or how to swing — high, middle, low.

In parts, it takes almost 0.20 second for the batter to identify the approaching ball and to identify the ball’s behavior. During the next 0.05 second, the batter makes the decision about the swing.

Via nerve transmission and neurotransmitter secretions at the neuromuscular junction it takes about 0.025 second for the message about the swing to reach the musculoskeletal system.

The swing itself takes about 0.150 second.

Based on the batter’s reaction information, let’s estimate that Hartley is fully concentrating on the batter and has about 0.30 second to identify that the sharp foul is headed his way. Let’s give him another 0.30 second to decide how to move to protect Isaac. Then another 0.025 second for neuromuscular transmission from brain to muscles. Finally, let’s give him 0.25 to perform the actual protective posture, which would probably take a little longer than swinging a baseball bat (Total 0.30 + 0.30 + 0.025 + 0.25 = 0.875 second). That leaves a 0.055 second margin to save Isaac (0.93 – 0.875 = 0.055).

If Keith Harley gets distracted fixing Isaac’s bottle or performing any other infant care, or turns away while communicating with his wife, or interacts with a vendor, or if the line shot is off of a home run hitter such as Joc Pederson; there’s no chance of taking a successful protective position.

Joc Pederson’s line shot could travel at 150.1 feet per second. The ball then travels from home plate to Hartley’s seat in 0.845 second. Protective reaction time insufficient.

See also …
Popular Mechanics Baseball Physics: Anatomy of a Home Run