Loading... Please wait...

Posted by John Dewan on Mar 28th 2017

Earlier this month at both the Sloan Analytics Conference in Boston and the SABR Analytics Conference in Phoenix, MLBAM’s StatCast team released details on a new statistic that they have started to report on flyballs to the outfield: Catch Probability. Catch Probability is a measure of how hard a catch is to make based on how far the batted ball is from the nearest outfielder and how long it has been in the air. Here is a full explanation of how it works from MLB.com. Because of our long-time passion for defensive metrics, we at Baseball Info Solutions (BIS) are particularly interested in their new statistic, especially in how it compares to Out Ratio, which is the basis of the Range and Positioning metric that serves as the foundational component of Defensive Runs Saved.

Catch Probability and Out Ratio are similar. Both measure how hard it is to catch a specific type of ball. Both rely on hang time to factor in difficulty. However, by measuring how far the fielder has to run, Catch Probability is measuring range by itself. Out Ratio measures range and positioning taken together in that it does not factor in the starting position of the outfielder.

The two metrics have differences, but they both get at the same question of how difficult a flyball was to catch. And both methods group plays with other plays having similar measurements from recent seasons to answer that question.

The MLB.com article shows a couple of examples that we can use to compare the two systems. The first is an awesome diving catch from Billy Hamilton from the Reds’ April 26 game against the Mets last season in the bottom of the fifth inning:

Catch Probability gives that flyball only a 7 percent chance of being caught. Hamilton had a long way to run on this play. Out Ratio gives center fielders a 35 percent chance of making the play. Catch Probability is just trying to measure range and ignores positioning.

Next up is Matt Kemp, who made his own diving catch last year on April 5 versus the Dodgers in the top of the fourth inning.

Similarly, Out Ratio is higher than Catch Probability. StatCast gives the flyball a 75 percent chance of being caught. Meanwhile, Out Ratio pegs the flyball at 100 percent; all 33 flyballs hit to this location with the same hang time from the last two years have been caught. Kemp’s positioning made it a tougher play.

As you can see from these two examples, bad positioning makes plays more difficult than they would be for outfielders if they simply had to rely on their range. This is as we would expect. Positioning has always been important in baseball, even more so in recent years. But while these two examples show instances of outfielders being positioned a bit worse than the average Out Ratio suggests, we would actually expect fielders to be positioned better than Out Ratio’s average more often than not. And so Catch Probability from StatCast is generally going to be higher than Out Ratio from BIS because of that advantage of positioning.

We look forward to more excellent work like this from the StatCast group. The kind of in-depth data the StatCast system collects will allow for measurement of defensive skills in finer and finer detail. Effectively splitting range and positioning into separate metrics is just the start. We are getting close to a day when we can tell you not only how much range a fielder has, but how quickly he reads the ball off the bat, how quick his first step is, how fast he is on approach, how well he takes routes to balls, and how sure-handed he is; and we will be able to hang a Runs Saved number on each part. The summation of all of those individual parts may not be too different from the numbers you’ve seen for years, but the level of detail will be incredible. For baseball analytics fans, the more the merrier.

**Out Ratio vs. Catch Probability**

March 28, 2017

Earlier this month at both the Sloan Analytics Conference in Boston and the SABR Analytics Conference in Phoenix, MLBAM’s StatCast team released details on a new statistic that they have started to report on flyballs to the outfield: Catch Probability. Catch Probability is a measure of how hard a catch is to make based on how far the batted ball is from the nearest outfielder and how long it has been in the air. Here is a full explanation of how it works from MLB.com. Because of our long-time passion for defensive metrics, we at Baseball Info Solutions (BIS) are particularly interested in their new statistic, especially in how it compares to Out Ratio, which is the basis of the Range and Positioning metric that serves as the foundational component of Defensive Runs Saved.

Catch Probability and Out Ratio are similar. Both measure how hard it is to catch a specific type of ball. Both rely on hang time to factor in difficulty. However, by measuring how far the fielder has to run, Catch Probability is measuring range by itself. Out Ratio measures range and positioning taken together in that it does not factor in the starting position of the outfielder.

The two metrics have differences, but they both get at the same question of how difficult a flyball was to catch. And both methods group plays with other plays having similar measurements from recent seasons to answer that question.

The MLB.com article shows a couple of examples that we can use to compare the two systems. The first is an awesome diving catch from Billy Hamilton from the Reds’ April 26 game against the Mets last season in the bottom of the fifth inning:

Catch Probability gives that flyball only a 7 percent chance of being caught. Hamilton had a long way to run on this play. Out Ratio gives center fielders a 35 percent chance of making the play. Catch Probability is just trying to measure range and ignores positioning.

Next up is Matt Kemp, who made his own diving catch last year on April 5 versus the Dodgers in the top of the fourth inning.

Similarly, Out Ratio is higher than Catch Probability. StatCast gives the flyball a 75 percent chance of being caught. Meanwhile, Out Ratio pegs the flyball at 100 percent; all 33 flyballs hit to this location with the same hang time from the last two years have been caught. Kemp’s positioning made it a tougher play.

As you can see from these two examples, bad positioning makes plays more difficult than they would be for outfielders if they simply had to rely on their range. This is as we would expect. Positioning has always been important in baseball, even more so in recent years. But while these two examples show instances of outfielders being positioned a bit worse than the average Out Ratio suggests, we would actually expect fielders to be positioned better than Out Ratio’s average more often than not. And so Catch Probability from StatCast is generally going to be higher than Out Ratio from BIS because of that advantage of positioning.

We look forward to more excellent work like this from the StatCast group. The kind of in-depth data the StatCast system collects will allow for measurement of defensive skills in finer and finer detail. Effectively splitting range and positioning into separate metrics is just the start. We are getting close to a day when we can tell you not only how much range a fielder has, but how quickly he reads the ball off the bat, how quick his first step is, how fast he is on approach, how well he takes routes to balls, and how sure-handed he is; and we will be able to hang a Runs Saved number on each part. The summation of all of those individual parts may not be too different from the numbers you’ve seen for years, but the level of detail will be incredible. For baseball analytics fans, the more the merrier.

The WBC and the 11th Inning RuleMarch 21, 2017 We still have a few weeks until the MLB season starts, but it almost feels like we are in the middle of a pennant chase thanks to the drama being provided by the World Baseball Classic. There has been a lot of energy in the stadiums, [...]

It feels like spring in Chicago where I live, and, more importantly, it feels like spring in Arizona and Florida where Spring Training is underway. Now that the majority of the offseason moves are behind us and Opening Day is just over a month away, it is time for our annual spring update of [...]

We are just getting started with Spring Training, but projection season is already in full swing, so let's take a peek at our Defensive Runs Saved (DRS) projections for 2017. Below are the teams with the best and worst projected up-the-middle fielders (i.e. catcher, second baseman, shortstop, and center fielder). This is often a good [...]

Earlier this week, Cubs GM Theo Epstein told reporters that they plan to give Kyle Schwarber some innings at catcher this spring so that he can serve as the team's third catcher during the season. One concern is whether Schwarber can handle catching duties given that he is less than a year removed from [...]

On Sunday, the Pirates announced their plan to reconfigure their defensive outfield in 2017, moving long-time center fielder Andrew McCutchen to right field, Gregory Polanco to left field, and defensive stalwart Starling Marte to center field. Based simply on their Defensive Runs Saved (DRS) totals from 2016, the move makes sense. Marte led [...]

Last week, the Atlanta Braves added Kurt Suzuki as their backup catcher behind Tyler Flowers. With this new addition, let’s examine how the Braves stack up defensively at the catcher position. There are five different components of Defensive Runs Saved (DRS) for catchers: Stolen Base Runs Saved, Bunts Runs Saved, Good Play/Misplay Runs Saved, Adjusted [...]

The Seattle Mariners have been busy this offseason with 11 trades. Including their deal with the Cubs back in July when they acquired Dan Vogelbach, there are now four likely changes to their starting lineup for 2017. Jarrod Dyson from the Royals and Mitch Haniger from the Diamondbacks will be replacing Nori Aoki and Seth [...]

In 2010, Alexei Ramirez saved 20 runs as a defender playing shortstop for the White Sox. He ranked 3rd in Major League Baseball behind only Alex Gonzalez (26) and Brendan Ryan (24). This past season, however, he was the worst shortstop defensively in all Major League Baseball costing his teams (Padres and Rays) 20 runs. [...]

Which outfielders had the best arms throughout the 2016 season? To answer this question, we use Outfield Arm Runs Saved. This metric evaluates fielders’ arms by considering both their ability to throw out baserunners without the use of a relay man—Outfield Kills—and the percentage of the time a baserunner attempts to take an extra base [...]