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Published byElisha Lambirth Modified about 1 year ago

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Modern Techniques for Evaluating Hitting Alan M. Nathan University of Illinois Batted ball analysis –Initial speed and angles –Landing point and hang time Swing analysis – Bat speed – Swing plane – Timing – “squaring up” 1

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Introductory Remarks Tradition techniques are “outcome- based” –BA, SLG, OPS, BABIP, … Modern techniques are “process- based”, independent of outcome –What constitutes a well-hit ball? –What constitutes a good swing? 2

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Tools for Modern Technique Baseball Info Solutions (BIS) –Batted ball landing point and hang time Hitf/x –Initial batted ball speed and angles TrackMan or Fieldf/x –All of the above (i.e., full trajectory) Physics –Relating batted ball to swing parameters 3

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Example: HITf/x Analysis 4 See Mike Fast, BPro, Nov. 16 & 22, 2011

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~50% of balls hit with BBS 90 mph are safe hits, regardless of VLA ~37% of balls hit with BBS 90 mph and 25 0 ≤VLA≤35 0 are HR BABIP HR What Constitutes “Good Contact”? Hitf/x from April 2009

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BABIP HR What Constitutes “Good Contact”? Hitf/x from April 2009 ~80% of balls hit with 10 0 ≤VLA≤15 0 are safe hits, regardless of BBS ~68% of balls hit with 10 0 ≤VLA≤25 0 and 60≤BBS≤80 mph are safe hits

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Potential of These Data Quantify “good contact” (GC) Establish outcome-inpependent metrics for hitting based on GC Investigate relationship between GC and pitching metrics Small sample size and sustainability Potential even greater if landing point & hang time are known –Ben Jedlovic’s talk at 2013 SABR Analytics

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Example Divide BBS-VLA space into rectangles For each rectangle, assign a value based on some useful metric –e.g., BA, SLG, Linear Weights, … For any hitter, weighted average can be computed to arrive at overall metric 8

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Landing Point/Hang Time (image courtesy of BIS) 9 Small horiz speedLarge horiz speed

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Ex: Two MLB Hitters (images courtesy of BIS) 10 Batter #1 Batter #2

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11 tof:R:bbs bbs:vla:R Comparing the two methods using TrackMan data BBS R

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12 tof:R:bbs bbs:vla:R BBS R Comparing the two methods using TrackMan data

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(bbs,vla) (tof,R)? 13 Considerable variation of R for fixed bbs,vla. All stadiums covered stadiums

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Why does initial velocity not determine landing point accurately? Variation in air density –Easy to control Variation in wind –Not so easy to control, except for covered Variation in spin –More in a mintue Variation in surface properties of ball –A topic of intense interest (to me!) 14

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Related question: Is greater “carry” a skill? In particular, is ability to put backspin on ball a skill? With both initial velocity vector and landing point/hang time, we can address this question for individual batters Related to swing parameters 15

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New Research Project Can batted ball data determine swing parameters? A very challenging physics problem In this talk I will –State the problem –Discuss progress in solving 16

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Bat Swing Parameters Bat speed determined by pitch and batted ball speed Fan: timing of swing Tilt: to swing plane Offset: “squaring up” 17 fan tilt E = offset

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Current State Bat swing parameters can predict batted ball parameters. –fan+tilt+offset HLA+VLA+spin axis Can batted ball parameters determine bat swing parameters?

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Simple Example: Straight Pitch, RHH, Tilt=0 0 19 E=0” E=-1” E=0 E=+1” Fan=0 0 Fan=-15 0 Fan=15 0

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Simple Example: Straight Pitch, RHH, Tilt=45 0 20 E=-1” E=0 E=+1” Fan=0 0 Fan=-15 0 Fan=15 0

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A Brief Aside: Spin of a Batted Baseball 2000 fps 120 mph friction normal force

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Fly balls break toward foul line 22 45 0 -45 00 LF RF

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Effect of tilt on spin axis 23

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Tilt Balls hit to CF slice 24 RHH LHH

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Current State of Affairs Spin axis might be able to determine tilt angle Spin axis can be determined from trajectory hang time backspin lateral deflection sidespin spin axis ~ tan -1 (sidespin/backspin) Work still in progress but It looks promising that HLA+VLA+spin axis fan+tilt+offset 25

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Summary/Outlook We have some new tools for evaluating batting based on process rather than outcome Determining swing parameters from batted ball data looks promising but still a work in progress Progress on both fronts would benefit greatly from existing data that are not readily available 26

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