Statistical Analysis: FB/GB/LD Rates


Looking at the end results of an at bat can be misleading sometimes. Not all singles are created equally. This is where batted ball data can come into play.

FB (Fly Ball) Rate: The percentage of batted balls which are considered flyballs. To me, this is judged as any ball that a fielder can take time and get undet to make a play on.

GB (Ground Ball) Rate: The percentage of batted balls considered ground balls. This one is pretty self-explanatory, as it is any batted ball which hits the ground prior to having the opportunity for a fielder to make a play. It also must hit the ground in the infield.

LD (Line Drive) Rate: The percentage of batted balls considered to be line drives. These are generally the most solidly hit balls, and have a much better chance of resulting in a positive outcome for the hitter.

What can these ratios tell us?

Generally, the higher a player’s LD ratio is, the more likely they are to have success as a hitter. Since line drives are generally the best hit balls, they are more likely to lead to success.

Home run hitters tend to have higher LD and FB rates,and speedy hitters tend to be more successful if they have higher GB rates, as this tends to allow them to use their speed to their advantage. Let’s look at some examples:

Aaron Hill hit 36 HR in 2009, easily doubling his previous career high of 17, set in 2007.

2007: .291, 17 HR, .459 SLG – 20.8% LD, 40.3% GB, 38.9% FB
2009: .286, 36 HR, .499 SLG – 19.6% LD, 39.5% GB, 41% FB

The key to notice with Hill is that his FB% went up by 2% from the 2007 season. While this is not a substantial enough jump to completely show the home run total as a fluke, it is something to watch with him as his previous full seasons he had not hit above 36% flyballs.

Ben Zobrist had a breakout season in 2009, hitting 27 HR, also more than double his previous high of 12 in 2008 (albeit in reduced playing time).

2009: .292, 27 HR, .543 SLG, 20% LD, 41.5% GB, 38.5% FB

For Zobrist, it was his line drive % which tells us his story. In 2008, Zobrist had only 13.5% line drives, while he had been at around 20% or higher previously in his career. Since arriving in the Majors (albeit briefly) in 2006, he had been reducing his GB rate, and seeing improvement in both FB and LD as a result. By reducing his GB%, he was making more solid contact and seeing improved results as a by-product.

How can we use this information?

Realistically, this data is best used in conjunction with BABIP to help determine the likelihood a player will repeat the statistics they had in the previous season.

What about using these stats for pitchers?

Pitchers have, realistically, the opposite goal and can see what kind of success they are having based on how low their LD% is. Odds are that if hitters are not hitting line drives, they are not making good contact, and as a result are less likely to reach safely.

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