Last week, Ben Lindbergh and Mitchell Lichtman provided evidence at The Ringer that the baseball currently being used in major league games is juiced. At FiveThirtyEight, Rob Arthur did more of the same. A springier baseball, they said, with lower seams and a smaller circumference, would lead to the ball flying several feet farther on average. This increase in distance on batted balls would likely account for much of the huge spike we have seen in home runs over the past few seasons.
The juiced-ball theory makes sense, and there's evidence to corroborate it. Adjacent to the juiced-ball theory, however, has been the much-ballyhooed "fly ball revolution." In recent years, several players have altered their strategies and swing planes in an effort to produce more and harder-struck fly balls, which would subsequently lead to more extra-base hits and homers.
Such an approach doesn't work for all players, and successful hitting isn't as simple as adopting a "try to hit home runs" strategy. Still, it can and has helped several players break out, such as Josh Donaldson and Justin Turner in recent years, or Yonder Alonso this year. When it comes to the Yankees, it looks like Brett Gardner might be among the fly ball revolutionaries.
It's no secret Gardner has enjoyed a surprising season at the plate. He's cooled off a bit recently, but his numbers are still strong across the board: career-highs in slugging (.484) and isolated power (.218) have culminated in a career-best 115 OPS+ for Gardner. He's on pace for his best season by WAR since 2010, his age-26 season. To do so at age-33 is a bit of a shock, and he might have a fly ball-oriented approach to thank.
One of the tenets of the fly ball revolution is that of swinging hard and for the fences. In selling out for power, oftentimes fly ball seekers can trade away some contact. Gardner has always had excellent contact skills, but this year, we've seen those skills erode slightly. Per FanGraphs, Gardner's contact rate on pitches out of the zone has fallen from 75% last year to 70% this year, and his contact rate on pitches in the zone has ticked down from 92% to 91%.
That's not a massive difference in contact rate, though, and a subsequent increase in fly balls and power would seem to be a fine trade-off. Indeed, Gardner is setting career-highs this year in fly ball rate (37.4%), fly ball plus line drive rate (59.3%) and pull rate (41.1%). In essence, Gardner appears to have traded some contact in order to pull a bunch more balls in the air, which, when playing at a home park like Yankee Stadium, sounds like a smart idea.
However, that doesn't necessarily mean that he's traded a bit of contact ability in exchange for better-struck batted balls. Just because he's hitting the ball in the air more doesn't mean he's definitely hitting it with more authority. Statcast can help here. Turning to the exit velocity leaderboards, Gardner's average exit velocity has actually hardly budged, moving from 85 mph last year to 86 mph this year, with both marks coming in below league average.
In the face of this, you might reasonably be skeptical that Gardner has actually improved his batted ball profile at all. Yet, average exit velocity isn't the be-all-end-all. Average exit velocity would posit that a player who struck one ball at 100 mph and one at 50 mph did the same job as one who hit two batted balls at 75 mph. In reality, the player that struck a 100 mph ball is likely to have produced much more value than the player who hit two 75 mph balls, balls that are likely to turn into outs. The average isn't everything: sometimes, it pays to hang out more at the extremes.
It's possible that Gardner has managed a greater number of dangerous batted balls without significantly improving his average exit velocity. Digging a little deeper on the Statcast leaderboards, that appears to be the case. Last year, just 24% of Gardner's batted balls were struck at 95+ mph. This year, that rate is up to 35%, which is close to league average.
Going even further, I pulled up the rate at which Gardner struck balls at launch angles between 20 and 40 degrees the past two years (i.e., the rate at which he's put balls in the air). Last year, just 16% of Gardner's batted balls fell into that range. This year, that rate is up to 27%. On those batted balls, Gardner is hitting .327 with a 1.135 slugging percentage. Gardner is definitely hitting dangerous batted balls at a greater rate this year, and if he's purposefully trying to hit more such batted balls, that decision has paid off so far.
There's no way to tell if Gardner has purposefully changed his strategy to try to hit for more power, short of simply asking him if he has, and even then, not all players prefer to be forthcoming about their on-field strategies. Regardless of his intention, Gardner almost perfectly matches the profile of a hitter who has traded a bit of contact in order to hit more air balls and hit them with increased authority. This is new for Gardner, so there's no telling if he can keep it up all year, but he's kept it up this far, and the result has been a career-year at the plate.