Pompey's plays a lesson in Catch Probability

New Statcast metric helps explain why Canada CF catches one deep fly ball but not another

Pompey's plays a lesson in Catch Probability

How much credit should an outfielder receive for a catch he makes? Conversely, how much blame should he shoulder when he doesn't track down a fly ball?

These questions get at the heart of Catch Probability, a Statcast™ metric that is new for 2017. And with Statcast™ in action on Thursday night at Marlins Park, where the Dominican Republic earned a 9-2 win over Canada in the first round of the World Baseball Classic, the two teams provided a pair of plays that make for a great introduction.

Both teams resume play at Marlins Park on Saturday, when Canada takes on Colombia and the Dominican Republic faces Team USA. World Baseball Classic games air live on MLB Network and on MLB.TV in the U.S.

• Statcast™ introduces Catch Probability for 2017

In the middle of everything were Dominican Republic first baseman Carlos Santana and Canada center fielder Dalton Pompey. In the fifth inning, Santana smacked a long double over Pompey's head. An inning later, on another deep drive to center, Pompey was able to lay out for a diving catch.

Unveiling Catch Probability

So what was the difference?

It wasn't something called Opportunity Time, which is clocked from the pitcher's release to when the ball is projected to drop, measuring how much time the outfielder has to get where he needs to go. On both plays, Pompey had an Opportunity Time of exactly 4.7 seconds.

It wasn't Pompey's sprint speed, either. He topped out at a rate of 27.1 feet per second on the double, compared with 26.5 feet per second on the catch (30 feet per second is considered elite, Billy Hamilton-level speed).

• Billy Hamilton's best Five Star catches

In fact, the difference was how far Pompey had to travel.

Santana struck the double with an exit velocity of 103.4 mph, at a launch angle of 20 degrees, giving it a Hit Probability of 68 percent. The drive was projected to travel 392 feet, and Pompey -- who was positioned 314 feet from home plate -- needed to cover 99 feet backward and toward left field.

Statcast: Relay nabs Bautista

The second Santana line drive had a similar launch angle (21 degrees) and lower exit velocity (97.2 mph), giving it a Hit Probability of just 37 percent. This ball was projected to fly only 373 feet, and Pompey -- perhaps as a result of the previous play -- was stationed deeper (321 feet from home). Therefore, the center fielder had a more manageable 72 feet to cover as he moved back and toward the right-center gap.

Now, back to Catch Probability. The metric combines Opportunity Time and the distance the outfielder needed to travel, and based on two seasons worth of data, determines how likely it was that the fly ball in question would be caught by that particular outfielder. It is expressed on a scale of 0-100 percent, ranging from impossible plays on the low end, to the easiest ones on the high end.

Catch probability a new metric

On Santana's double, Pompey's Catch Probability was only 7 percent. That made it a potential Five Star play, on a scale of one to five (see below). But on Santana's subsequent flyout, Pompey's Catch Probability actually was 86 percent. That made it "only" a Two Star play, despite a diving, tumbling finish that is sure to put it on highlight reels. (Remember: Pompey's top speed on the catch was slower than it was on the double, and he had a lot less distance to travel, which is why the play was not as difficult as the dive made it look).

0 to 25 percent -- 5 Star play*****
26 to 50 percent -- 4 Star play****
51 to 75 percent -- 3 Star play***
76 to 90 percent -- 2 Star play**
91 to 95 percent -- 1 Star play*

Generally speaking, we can grade the quality of a play based on the player's top speed, as measured in feet per second. So if you max out at 30 feet or more per second, you are in Hamilton territory. The bands break down like this:

5-star: 30 feet per fastest 1 second
4-star: 29 ft/sec
3-star: 28 ft/sec
2-star: 27 ft/sec
1-star: 25 ft/sec

On his diving catch, Pompey peaked at 26.5 ft/sec, which is right in with what you should see on a 2-star catch. And as it turns out, the 89 percent catch probability put it squarely in the 2-star range.

It is important to note one caveat, however. Catch Probability does not currently account for direction, a feature that will be added this season, and going back on a fly ball is generally more difficult than coming in on one. In other words, that 86-percent probability might be underrating Pompey's catch a bit.

Still, those two plays provide a glimpse at how Statcast™ will change how outfield defense is evaluated as we enter the 2017 season.

The World Baseball Classic runs through March 22. In the U.S., games air live exclusively in English on MLB Network and on an authenticated basis via MLBNetwork.com/watch, while ESPN Deportes and WatchESPN provide the exclusive Spanish-language coverage. MLB.TV Premium subscribers in the U.S. have access to watch every tournament game live on any of the streaming service's 400-plus supported devices. The tournament is being distributed internationally across all forms of television, internet, mobile and radio in territories excluding the U.S., Puerto Rico and Japan. Get tickets for games at Marlins Park, Tokyo Dome, Estadio Charros de Jalisco in Mexico, Petco Park, as well as the Championship Round at Dodger Stadium, while complete coverage -- including schedules, video, stats and gear -- is available at WorldBaseballClassic.com.

Andrew Simon is a research analyst for MLB.com. Follow him on Twitter @AndrewSimonMLB. This story was not subject to the approval of Major League Baseball or its clubs.