Is there an ideal ground ball rate for hitters? Should they be thinking about how many grounders they hit? Armed with some spreadsheets and a couple conversations with some Royals’ hitters, let’s see what we can discover.

First off, we can write off a simple answer. There is no correlation between ground-ball-to-fly-ball ratio and team runs scored or team weighted runs created. Teams are made up of individuals, and it might be folly to recommend one approach to Billy Butler as you would to Jarrod Dyson. Perhaps that’s partly what Eric Hosmer meant when he told me that you don’t want to “change too much from the natural fluidity of you swing — you got to this level with that swing.”

But we’ve been taught the adage that more fly balls mean more home runs. Billy Butler acknowledged he’s heard that before. And of course your ground-ball-to-fly-ball ratio is strongly (and negatively) correlated to power stats — more fly balls do mean more home runs. And also the relationship between ground-ball-to-fly-ball ratio and batting average on balls in play is fairly clear — more grounders mean more hits. The value of the home run outstrips the value of a hit, and that’s why GB/FB ratio is not well correlated to runs, or overall offensive value.

A cursory look at the fly ball leaderboard since 2003 shows multiple entries from Frank Thomas, Mark Reynolds, Jason Giambi and Jose Bautista. Even if ground balls turn into hits more often, the fly ball serves the slugger well, so sluggers turn to it more.

So it looks like there might be an ideal ground-ball-to-fly-ball ratio… for each individual hitter. We’re back to Hosmer’s quote about each individual swing, with an asterisk. Billy Butler talks about thinking only of “putting the barrel to the ball” when he’s at the plate, but there do seem to be variations on that theme for different types of players. Sluggers get the ball in the air a bit more, and speedsters put it on the ground.

Players do change, and players do search for a unique mix that works for them. Perhaps they were sluggers before but find themselves dwarfed by the sluggers in the big leagues. Perhaps they’d like a few more hits mixed in with their home runs.

Joey Votto talked about leveling his swing plane. Alex Gordon had much of the same revelation, brought on by his early struggles and his demotion in 2010. “Over the last couple of years I’ve tried to cut down on my fly balls and I’ve tried to cut down on my strikeouts,” he said, “because the easiest out in baseball — other than the strikeout — is the lazy fly ball.”

It’s hard to argue with his results. He’s progressively hit more ground balls, and his offense is a career-high 44% better than league average right now. It looks like ground balls (and fewer strikeouts) drove much of his improvement:

Year BB% K% ISO OBP Pull% GB/FB wRC+ 2007 6.8% 22.8% 0.164 0.314 41.3% 0.85 87 2008 11.6% 21.0% 0.172 0.351 42.2% 0.66 106 2009 11.1% 22.8% 0.146 0.324 39.8% 1.04 87 2010 12.1% 22.1% 0.140 0.315 43.2% 0.96 85 2011 9.7% 20.1% 0.200 0.376 43.8% 1.03 141 2012 10.1% 19.4% 0.160 0.368 36.4% 1.29 126 2013 5.3% 20.5% 0.189 0.373 36.9% 1.45 144

And the park means something. “In a big stadium like Kaufmann, a lot of fly balls just go to the warning track,” Gordon said. Even a unique hitter struggling to find the best ratio with respect to his own game might have to think about the park he calls home more often. Jed Lowrie mentioned this when he talked about the evolution of his swing in the different organizations and parks he found himself in. You don’t want to change your swing to suit your park too much — what if you get traded — and yet you play half your games there. Home runs are suppressed by 16% with respect to the average park in Kansas City, and yet the White Sox call The Cell home, which augments home runs by 24% over average. Maybe, when Gordon talks about how he “got carried away with hitting home runs” early in his career, maybe he wouldn’t have changed his swing like he did if he played in Chicago.

Can we see the difference starkly? On the left is a swing from 2008, when Gordon had one of his higher pull percentages and lowest ground-ball rates, and HD apparently didn’t exist. And on the right, the first of his four hits from his strong night against the Athletics on the 19th.

Maybe Alex Gordon has found his own unique ideal ground-ball rate. He’s certainly calmed his pre-swing movement down, and his swing plane looks more level. And you can see he’s right when he says he’s now more capable of covering the outside corner more now that his swing is more level and he’s not concentrating on pulling the ball. Gordon credits former hitting coach Kevin Seitzer for the advice, but he put in the hard work. He’s no longer “see the ball, hit the ball, try to crush the ball” as he used to be.

There’s one last asterisk here: the pitcher. Hitting coaches talk about hitting the ball where it is. Eric Hosmer called it “playing the situation, whatever it is that at-bat.” Alex Gordon said he is always “thinking about what the pitcher is trying to do.”

But we sort of know what the average pitcher is trying to do. Thanks to Jeff Zimmerman, we know 61% of all pitches are on the outside half of the plate. 45% of the pitches in the strike zone are in the bottom third of the zone. Butler said he’s always “looking from the knees to the waist because pitchers are taught to get outs at the knees.” There’s Gordon talking about the added plate coverage he has now. These are potentially good arguments for most hitters to consider a more level swing plane across the board.

Even if there is an argument for more ground balls, there isn’t quite an argument that there is one ideal ground-ball-to-fly-ball ratio for all hitters. Each has to find their own unique mix. For some, it might take a little time and some tweaks. For others, they’re just naturally able to barrel the ball from day one. But that relationship — between how level your swing is, and the amount of ground balls you produce — looks like a place you might start if you were struggling at the plate. It certainly worked for Alex Gordon.

Update: I took out a graph showing a negative correlation between HR/FB and GB/FB ratio because it really just was a graph of a correlation between GBs and HRs, and that’s obvious. Sluggers like to hit more fly balls!