The concept has picked up steam in the era with metrics like "Barrels," with the Cubs preaching there's "no slug on the ground" and with the explosion of infield shifts that have made life harder on ground-ball hitters.
"Slugging happens when the ball's hit in the air," veteran infielder David Freese said. "Especially now, the way infielders are lined up. Balls shot down the line, it's hard to get doubles. … With the launch angles, I think people are understanding that to slug, you have to hit the ball in the air."
The results speak for themselves. According to Statcast™, the Pirates batted .475 with an .875 slugging percentage on line drives and fly balls (not including popups) last season. They hit .247 with a .262 slugging percentage on ground balls.
"I do think it's a transition lane in which the game is going," Hurdle said. "You've seen some very good hitters have very good success with it. More conversations are being had analytically about it. … We're definitely having conversations."
According to Statcast™, the Pirates had an average launch angle of 10.3 degrees in 2016, the Majors' 27th lowest. But it's not as simple as telling players to hit the ball in the air. Hurdle held his hands inches apart to indicate the difference between an ideal line-drive swing plane and one that might lead to pop flies.
"It's a fine line with that," hitting coach Jeff Branson said. "The last thing you want to tell a guy is, 'We want to lift. We want to lift. We want to lift.' More times than not, if they start thinking about lifting, they lose concept of their body position and all that stuff, so everything starts to drop. They try to lift it rather than letting the lift happen."
Gregory Polanco is perhaps the best example. Polanco struggled when he tried to lift the ball; he'd roll over balls or pop them up. He posted a 49.5 percent ground-ball rate as a rookie and a 45.4 percent mark in 2015. That number dropped to 38.8 percent last year as his line-drive rate (24 percent) and fly-ball rate (37.1 percent) increased.
But Polanco didn't set out to hit fly balls; he struggled when he tried that. He tightened up his swing and focused on spraying "low and hard" line drives, he said. His average launch angle increased from 10.3 degrees in 2015 to 12.9 degrees in 2016, and his OPS climbed from .701 to .786.
Freese, who has found success as a ground-ball hitter, said he'd probably delve deeper into contact points and launch angles if he was just starting his career. Along those lines, Hurdle said the Pirates have talked about teaching the concept early on to young hitters.
They may not be interested in crunching the numbers, but they'll appreciate the results.
"I think it's important," Freese said. "You can definitely learn your swing and learn sometimes why your numbers are what they are based on how hard the ball's coming off your bat and your launch angle."