Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.
Like A Rock:
Exploring How a Catcher's
Movement Affects Framing
Rob Arthur
@No_Little_Plans
fivethirtyeight.com
Dan Turken...
Catcher Framing Is A Real And Measurable Skill
@MetsUmp
Called Strike
40% of the time
with average
catcher
Called Strike
3...
Current Catcher Framing Metrics Measure
The Outcome, But Not The Process
Catcher Skill Level
Hitter Skill Level
Foot Speed...
Video Analysis Can Tell Us
How
Catcher Framing Works
http://grantland.com/features/studying-art-pitch-framing-catchers-suc...
Measuring Movement
Source: Bloomberg Video
.05s .05s
The Catch
We Select A Very Particular Set of Pitches
Selecting Only:
• Called strikes
• RHH vs. RHP
• At the catcher’s home ballpark...
Catcher Framing Is All About Movement
http://fivethirtyeight.com/features/buster-poseys-pitch-framing-makes-him-a-potentia...
Comparing Across Ballparks Is Difficult (for now)
Different Viewing Angles Create
A Parallax Problem
en.wikipedia.org
Normalizing Pixel Movement
Normalized movement =
∆ 𝑖
𝐸[∆]
In English: The movement in a given frame divided by
the average...
Good And Bad Catchers Have Different Patterns
Posey, Flowers, Zunino,
Castro
Ruiz, James McCann,
Nick Hundley
Bad Framers Do Not Pause
Conclusions and Limitations
• We can analyze catcher framing with video.
• Good catchers display a particular pause soon a...
We can do more (or at least we think we can)
7/28/2013 – Josh Thole catching: 46% strike chance
(Source: Baseball Prospect...
6/25/2013 - J.P. Arencibia catching: 93% strike chance
(Source: Baseball Prospectus/Pitch Info)
More Granular Catcher Movements
• Identify candidate points to track
• Head, shoulders, knees and gloves (knees and gloves...
An Automated Approach
• Identify glove position at release
• i.e. CommandFX
• Identify position of the other important poi...
This is Hard
• Use a set of techniques known as computer vision (CV)
• Lots of well-known approaches for identifying and t...
The Manual Approach
• Choose good pitches
• Find the release frame
• Draw calibration line on front of home plate
• Mark t...
That Thole Frame Job
Point Release to
Catch (in.)
Deg Catch to Ump
Mvmt (in.)
Deg Release to Ump
Mvmt (in.)
Deg
Right
Knee...
And Then There’s J.P.
Point Release to
Catch (in.)
Deg Catch to Ump
Mvmt (in.)
Deg Release to Ump
Mvmt (in.)
Deg
Right
Kne...
How Can We Use This in Player Evaluation?
• Expected catcher movement based on a lot of factors
• Pitch type
• Pitch locat...
Questions?
Rob: @No_Little_Plans
Dan: @dturkenk
Appendix
Like a Rock: Exploring How a Catcher's Movement Affects Framing
Like a Rock: Exploring How a Catcher's Movement Affects Framing
You’ve finished this document.
Download and read it offline.
Upcoming SlideShare
Unternehmen in Europa
Next
Upcoming SlideShare
Unternehmen in Europa
Next
Download to read offline and view in fullscreen.

Share

Like a Rock: Exploring How a Catcher's Movement Affects Framing

Download to read offline

Saber Seminar presentation on 8/22/2015 in Boston.

Like a Rock: Exploring How a Catcher's Movement Affects Framing

  1. 1. Like A Rock: Exploring How a Catcher's Movement Affects Framing Rob Arthur @No_Little_Plans fivethirtyeight.com Dan Turkenkopf @dturkenk
  2. 2. Catcher Framing Is A Real And Measurable Skill @MetsUmp Called Strike 40% of the time with average catcher Called Strike 30% of the time when Carlos Ruiz is catching Called Strike 50% of the time when Buster Posey is catching
  3. 3. Current Catcher Framing Metrics Measure The Outcome, But Not The Process Catcher Skill Level Hitter Skill Level Foot Speed Plate Discipline Raw Power Reputation With Umps Technique Command of Pitchers ??? PITCHf/x
  4. 4. 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/
  5. 5. Measuring Movement Source: Bloomberg Video .05s .05s The Catch
  6. 6. We Select A Very Particular Set of Pitches Selecting Only: • Called strikes • RHH vs. RHP • At the catcher’s home ballpark Filtering If: • The batter checked his swing • The captured pixels failed to include the catcher • The pitcher’s foot got in the frame
  7. 7. Catcher Framing Is All About Movement http://fivethirtyeight.com/features/buster-poseys-pitch-framing-makes-him-a-potential-mvp/
  8. 8. Comparing Across Ballparks Is Difficult (for now)
  9. 9. Different Viewing Angles Create A Parallax Problem en.wikipedia.org
  10. 10. Normalizing Pixel Movement Normalized movement = ∆ 𝑖 𝐸[∆] In English: The movement in a given frame divided by the average movement across the catch. What this can’t tell us: which catchers are the quietest in their reception. What this can tell us: when, during the reception, a given catcher is quietest (relative to other parts of the reception).
  11. 11. Good And Bad Catchers Have Different Patterns Posey, Flowers, Zunino, Castro Ruiz, James McCann, Nick Hundley
  12. 12. Bad Framers Do Not Pause
  13. 13. Conclusions and Limitations • We 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…
  14. 14. 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)
  15. 15. 6/25/2013 - J.P. Arencibia catching: 93% strike chance (Source: Baseball Prospectus/Pitch Info)
  16. 16. More Granular Catcher Movements • Identify candidate points to track • Head, 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 models • Should shrink the per catcher variance • Allows for predictions of framing ability based on video of movement
  17. 17. An Automated Approach • Identify glove position at release • i.e. CommandFX • Identify position of the other important points at release • Determine movement vectors for each • Distance and direction • Simplifying assumption: use start and end points rather than actual paths
  18. 18. This is Hard • Use a set of techniques known as computer vision (CV) • Lots of well-known approaches for identifying and tracking objects in images/videos • But, we have A LOT of complications • Calibration: parallax, distance, t0 • Markerless tracking: how can we identify the points we’re interested in at scale? • What part of the glove do we use to measure glove position? What if the catcher doesn’t set up before the pitch is released? • Etc. • Etc.
  19. 19. The Manual Approach • Choose good pitches • Find the release frame • Draw calibration line on front of home plate • Mark the points we care about • Rinse and repeat for the catch frame and the ump’s first movement frame (estimated) • Overlay them • Figure out the movement vectors
  20. 20. That Thole Frame Job Point Release to Catch (in.) Deg Catch to Ump Mvmt (in.) Deg Release to Ump Mvmt (in.) Deg Right Knee 1.6 58 1.4 -83 1 0 Left Knee 11.9 -7 1 -45 11.1 -4 Right Shoulder 2.8 -60 0.9 -79 2 -52 Left Shoulder 1.5 -21 0.7 0 0.9 -37 Head (center) 0.7 76 0.9 -68 0.5 -18 Glove (center) 7.5 67 5.1 -74 4.8 26
  21. 21. And Then There’s J.P. Point Release to Catch (in.) Deg Catch to Ump Mvmt (in.) Deg Release to Ump Mvmt (in.) Deg Right Knee 3.1 11 1 -53 2.8 30 Left Knee 1.9 77 5.8 39 4.4 24 Right Shoulder 0.2 0 1.7 -45 1.9 -41 Left Shoulder 3.1 -32 2.6 -51 5.6 -41 Head (center) 1.5 -34 4.5 -10 5.9 -16 Glove (center) 19.3 -36 3.3 -76 16.9 -29
  22. 22. How Can We Use This in Player Evaluation? • Expected catcher movement based on a lot of factors • Pitch type • Pitch location • Runners • Etc. • Probably can’t just figure out average movement for a catcher and correlate to framing • Will need to be done on a pitch by pitch basis and summed • MILB expected movement probably not the same as MLB • Largely due to pitcher command
  23. 23. Questions? Rob: @No_Little_Plans Dan: @dturkenk
  24. 24. Appendix
  • RyanFroistad

    Aug. 25, 2015

Saber Seminar presentation on 8/22/2015 in Boston.

Views

Total views

2,231

On Slideshare

0

From embeds

0

Number of embeds

113

Actions

Downloads

9

Shares

0

Comments

0

Likes

1

×