One father who failed to listen sat in Harrison’s section with a 1-year-old boy in his lap.

“I said, ‘Watch the batter,'” Harrison recalled. “He wasn’t watching the batter and the ball hit the kid right in the face. He took the kid and ran out of here.”

Harrison spent nearly four decades as an elementary school teacher in Oakland, with Stanley Burrell – better known as MC Hammer – among his pupils. So he came into this retirement job fully equipped with the patience to repeat himself time and again to a crowd less than receptive to his message. But there will be less of a need for that now that the Sky Sox have followed a recent Minor League Baseball recommendation to extend safety netting through the far end of each dugout.

Every lower-level seat at Security Service now has a net separating fans from the playing field, whereas before the netting covered only the area behind home plate but stopped just short of each dugout. The netting extends only vertically, so balls popped up can still turn into souvenirs. But the hope is that the low, high-velocity foul balls and broken or thrown bats no longer turn into dangerous projectiles.

It’s a move that wasn’t mandated by Minor League Baseball, but figures to soon be the norm at all professional ballparks. Major League commissioner Rob Manfred followed studies of fan safety with a recommendation that all big league ballparks extend their netting prior to the 2016 season.

The flip side is a net can be seen as obstructing a fan’s view, and it also limits the ability for player-fan interaction, as it will be trickier for players to find a way, for example, to toss an out-of-play ball into the stands.

Sky Sox general manager Tony Ensor said the netting fits with the family atmosphere he strives to produce at a stadium where most seats have relatively close proximity to the batter’s box. But he’s heard comments “from both sides of the spectrum” after one homestand.

“The protection of our fans and the fans’ safety is part of that,” Ensor said. “We want people to come out here and enjoy games with their family and not have to worry about balls flying into the stands at such close range.”

Ensor stressed that the netting material selected from Dyneema is among the most transparent in the industry. He also said solutions to help with interaction, such as a way to make the extra netting retractable before and after games, is being considered.

But ultimately, safety is likely the driving force behind any further decisions. A study from Bloomberg News found that in 2014 there were 1,750 fans injured by balls entering the stands, the extent of which varied from cuts and bruises to broken bones, skull fractures and nerve and brain damage.

“Those balls come over down in the box seat areas very quickly and it’s hard for fans to react, especially if their attention is being drawn to something else,” Ensor said. “We just thought this was a great way for people to really enjoy Sky Sox baseball and not have to pay 100 percent attention to every single pitch that’s thrown in a game.”

It took just two innings into the Sky Sox home season for the first screaming foul ball headed for the stands to be caught in the new netting. That ball was hit down the first baseline, so it wouldn’t have been a threat to Harrison’s sections. But there will be plenty this season.

“A lot of people come out here to socialize, and they’re not watching the game,” said Harrison, who ushered games for the Oakland Athletics for five years before retiring to Colorado Springs. “You go down and tell them, ‘There’s a left-handed batter up here and the guy’s throwing 95 miles per hour.’ And it’s just like drivers, they don’t follow the speed limit.”