PowerPoint Presentation

Like A Rock: Exploring HowaCatcher's Movement Affects FramingRob Arthur@No_Little_Plansfivethirtyeight.com

Dan Turkenkopf@dturkenk

Catcher Framing Is A Real And Measurable Skill@MetsUmpCalled Strike40% of the timewith average catcherCalled Strike30% of the timewhen Carlos Ruiz is catchingCalled Strike50% of the timewhen Buster Posey is catching

How we measure catcher framing2

Current Catcher Framing Metrics Measure The Outcome, But Not The ProcessCatcher Skill LevelHitter Skill LevelFoot SpeedPlate DisciplineRaw PowerReputation With UmpsTechniqueCommand of Pitchers???Exit VelocityPITCHf/xStatcast

Video Analysis Can Tell Us How Catcher Framing Works

http://grantland.com/features/studying-art-pitch-framing-catchers-such-francisco-cervelli-chris-stewart-jose-molina-others/

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Measuring Movement

Source: Bloomberg Video

.05s.05sThe Catch

We Select A Very Particular Set of Pitches

Selecting Only:Called strikesRHH vs. RHPAt the catchers home ballparkFiltering If:The batter checked his swingThe captured pixels failed to include the catcherThe pitchers foot got in the frame

Catcher Framing Is All About Movement

http://fivethirtyeight.com/features/buster-poseys-pitch-framing-makes-him-a-potential-mvp/

Summary of 538 article7

Comparing Across Ballparks Is Difficult (for now)

Compare gifs of different camera angles8

Different Viewing Angles Create A Parallax Problemen.wikipedia.org

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Normalizing Pixel Movement

Good And Bad Catchers Have Different Patterns

Posey, Flowers, Zunino, CastroRuiz, James McCann, Nick Hundley

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Bad Framers Do Not Pause

Now that we can examine relative movement, lets look at *when* good vs. bad catchers move.12

Conclusions and LimitationsWe can analyze catcher framing with video.Good catchers display a particular pause soon after receiving the pitch, and steady their gloves just prior.We are limited by parallax and other issues.

But, Dan is going to fix all of our problems

We can do more (or at least we think we can)

7/28/2013 Josh Thole catching: 46% strike chance (Source: Baseball Prospectus/Pitch Info)

6/25/2013 - J.P. Arencibia catching: 93% strike chance(Source: Baseball Prospectus/Pitch Info)

More Granular Catcher MovementsIdentify candidate points to trackHead, shoulders, knees and gloves (knees and gloves)

Measure how those points move across the timeline of the pitch

Correlate the movement to the framing random effects

Add movement into the framing mixed modelsShould shrink the per catcher varianceAllows for predictions of framing ability based on video of movement

An Automated ApproachIdentify glove position at releasei.e. CommandFX

Identify position of the other important points at release

Determine movement vectors for eachDistance and directionSimplifying assumption: use start and end points rather than actual paths

This is HardUse a set of techniques known as computer vision (CV)Lots of well-known approaches for identifying and tracking objects in images/videosBut, we have A LOT of complicationsCalibration: parallax, distance, t0Markerless tracking: how can we identify the points were interested in at scale?What part of the glove do we use to measure glove position? What if the catcher doesnt set up before the pitch is released?Etc. Etc.

The Manual ApproachChoose good pitchesFind the release frameDraw calibration line on front of home plateMark the points we care aboutRinse and repeat for the catch frame and the umps first movement frame (estimated)Overlay themFigure out the movement vectors

That Thole Frame JobPointRelease to Catch (in.)DegCatch to Ump Mvmt (in.)DegRelease to Ump Mvmt (in.)DegRight Knee1.6581.4-8310Left Knee11.9-71-4511.1-4Right Shoulder2.8-600.9-792-52Left Shoulder1.5-210.700.9-37Head (center)0.7760.9-680.5-18Glove (center)7.5675.1-744.826

And Then Theres J.P.PointRelease to Catch (in.)DegCatch to Ump Mvmt (in.)DegRelease to Ump Mvmt (in.)DegRight Knee3.1111-532.830Left Knee1.9775.8394.424Right Shoulder0.201.7-451.9-41Left Shoulder3.1-322.6-515.6-41Head (center)1.5-344.5-105.9-16Glove (center)19.3-363.3-7616.9-29

How Can We Use This in Player Evaluation?Expected catcher movement based on a lot of factorsPitch typePitch locationRunnersEtc.Probably cant just figure out average movement for a catcher and correlate to framingWill need to be done on a pitch by pitch basis and summedMILB expected movement probably not the same as MLBLargely due to pitcher command

Questions?Rob: @No_Little_PlansDan: @dturkenk

Appendix