For each grounder, we then convert the bip coordinates into the angle at which the grounder was hit off of the bat. We estimate the starting location for each fielder as the (x,y) location in the field where each position has the highest overall probability of making a successful play. Our BIS data does not provide a key piece of information for each g-bip: the location of each fielder before the ball was hit. Estimating starting locations for each position Our evaluation procedure consisted of the following steps:ġ. We defined any play where one out or more was made as "successful". For each grounder ball-in-play (g-bip), we have the (x,y) coordinates in the field where the g-bip was fielded, a "velocity" classification (ranging from 1-5) for the g-bip, as well as the number of outs made on the play. Our raw data is from Baseball Info Solutions. Methodology for Grounder Balls-In-Play (g-bip) Instead of tabulating fielding events within discrete zones, we fitĬontinuous probability distributions to each fielder based on their past fielding events. Is, instead of a set of zones or vectors.
Ideally, the baseball field could be treated as the continuous playing surface that it actually Still based on dividing the baseball field into discrete zones and vectors, and tabulating events withinĮach zone.
However, despite being obvious improvements on previous methods, both of these approaches are These statistics are more accurate measures of fielding ability. Recent techniques such as Ultimate Zone Rating or the Plus-Minus system from Theįielding Bible are based on the tabulation of both positive and negativeįielding events. However, tabulating errors isn't a good measure ofĪbility without a corresponding measure that credits a player for making a play that most players wouldn't Their unsuccessful play should have been successful. The much-maligned error statistic is a subjectiveĪttempt at discretising this phenomenon: players are assigned an error if the official scorer deems that The central difficulty with fielding is that we are trying to evaluate players on aĬontinuous playing surface where we must take into account not just whether a successful play was made, but MostĮvents in baseball, such as hitting events, are discrete which makes them easy to tabulate and model One of the aspects of baseball that is the hardest to quantify and evaluate is fielding ability. SAFE: Spatial Aggregate Fielding Evaluation
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