What's the best kind of contact a hitter can make? Line drives, naturally. According to the FanGraphs Library, a line drive produces about 1.26 runs per out, where fly balls produce 0.13 runs per out and ground balls produce 0.05 runs per out. Can you believe how huge that difference is? As a rule, line drives are worth nearly 10 times as much as a fly ball, and a little over 25 times as much as a ground ball!
You'd think that line drive percentage would be a massive driver of offensive performance, on a practical level. I mean, consider this huge per-out disparity that I referenced above! You'd have to assume that there'd be a solid correlation between LD% (the measurement of how many hits are line drives) and wOBA / wRC+, which are (as you probably know) offensive metrics that encapsulate and accurately weight hitting performance.
Well, this year, the best offense in the National League has belonged to the Milwaukee Brewers.* The Brewers also have the worst LD% in all of baseball, checking in at 18.9%. Sounds counter-intuitive, doesn't it? How could the team with the best offense in the league, hit the least of these extraordinarily-valuable types of batted ball?
* Note: Actually, both the Brewers and the Cardinals have a wRC+ of 107. I give the Brewers extra credit in this statement, because they actually have a .332 wOBA as compared to the Cardinals' .329 wOBA.
So how are they doing it?
I vote that we start at the top. And "the top" refers to the best hitter on the Brewers, reigning NL MVP Ryan Braun. Braun is a powerful slugger with plus power and hit tools, as you probably know. He's managed to rack up 40 HR, 29 SB and a .419 wOBA in this season, and is making a compelling case to repeat as MVP. But Braun, despite that gaudy wOBA and a massive 165 wRC+, has only a LD% of 17.6%. That's small. it's smaller than the Brewers' team line drive percentage of 18.9%. It's smaller than the league average of 20.9% this season.
Weirder still, FB% usually sits around 44% for slugging power hitters. Braun's FB% is only at 38.9% for the season, which is not far off his career mark. Braun is seeing a huge number of his balls in the air leave the park as home runs. 23.5% of them, to be exact.
From all accounts, it looks like Braun is doing double-duty, doing his part to bring down his team's LD%, while massively improving his team's wOBA and wRC+ through his phenomenal hitting.
In addition to Braun's batted-ball weirdness, let's remember that batted-ball data isn't perfectly reliable. Batted ball data is determined by hand, by official scorers, and is subject to opinion and human error. Oftentimes, the difference between a line drive and a fly ball can be insignificant.
Line drive percentage is a tricky thing ... for a type of batted ball that is so valuable, LD% fluctuates quite a bit. Ryan Braun proves that you don't need to have a gigantic LD% to be a phenomenal hitter. And the Brewers are proving that you can be a solid offensive squad without a high LD% as well -- so long as you have a world-class hitter nestled in the heart of your lineup.
All stats from FanGraphs, and are current as of Sunday, 9/23/12.