Baseball Glossary › Groundout-to-Airout Ratio
Groundout-to-Airout Ratio (GO/AO)
Groundout-to-airout ratio (GO/AO) divides the number of ground balls turned into outs by the number of balls in the air turned into outs. Bunts are excluded, and air outs include fly balls and line drives. A GO/AO above 1.00 means more groundouts than air outs, which marks a ground-ball pitcher or hitter.
Formula
Worked example (illustrative numbers): a pitcher's outs include 240 groundouts and 160 air outs.
GO/AO = 240 / 160 = 1.50
He gets one and a half ground-ball outs for every out in the air
What to Know
For pitchers, a higher GO/AO is often a good sign, because balls in the air can become the most damaging result of all, a home run. But fly-ball pitchers can still thrive if they get weak contact or plenty of strikeouts.
For hitters the ratio is used less, though fast runners may prefer more grounders because some become infield hits. Power hitters usually want the ball in the air at a healthy launch angle.
GO/AO only counts batted balls that became outs, so it is a different view from batted-ball rates that count every ground ball or fly ball. It pairs well with BABIP when judging contact quality.
Frequently Asked Questions
What does GO/AO mean in baseball?
GO/AO stands for groundout-to-airout ratio. It is the number of outs made on ground balls divided by the number of outs made on fly balls and line drives.
How is GO/AO calculated?
Divide groundouts, not counting bunts, by air outs, which are fly-ball and line-drive outs. A pitcher with 240 groundouts and 160 air outs has a GO/AO of 1.50.
Is a high GO/AO good for a pitcher?
Often, yes. Ground balls rarely leave the park, so a high GO/AO pitcher limits home runs. Fly-ball pitchers can still succeed by getting weak contact or many strikeouts.
What does a GO/AO above 1.00 mean?
It means more outs came on ground balls than in the air. Below 1.00 means more air outs than groundouts, typical of a fly-ball pitcher or a power hitter.
Do bunts count in groundout to airout ratio?
No. MLB's definition leaves bunts out of the groundout total, so sacrifice bunts and bunt outs do not change the ratio.
Does GO/AO apply to hitters?
Yes, but it is used less often. Speedy hitters may benefit from more ground balls, since some turn into infield hits, while sluggers generally want more balls in the air.
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Sources
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