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Probabilistic Model of Range. David F. Pinto Baseball Musings www.baseballmusings.com. Construction of Model. Direction. p ( out|D,T,S,B,P,PK ) All Fielders. Trajectory (Ground, Fly, Line). Weighting: Visit in Play > 0.5 Then Visit In Play Else 2*Visit in Play/All in Play.
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Probabilistic Model of Range David F. Pinto Baseball Musings www.baseballmusings.com
Construction of Model Direction p(out|D,T,S,B,P,PK) All Fielders Trajectory (Ground, Fly, Line) Weighting: Visit in Play > 0.5 Then Visit In Play Else 2*Visit in Play/All in Play p(out|D,T,S,B,P,PK) Smoothed Speed Handedness, Batters and Pitchers p(out|D,T,S,B,P,PK) Visiting Fielders Park
History of Fielding Stats • Assists, Putouts, Errors, Fielding Percentage, Games at position • No Context • Range Factor (Assists + Putouts)/Game • Last 1980s (Assists + Putouts)/(9 Innings) • Zone Rating • Ultimate Zone Rating (UZR), PMR
Defensive Efficiency Rating • DER measures the probability that a fieldable ball in play results in at least one out. • Similar to 1- BABIP (BA on Ball in Play) • BABIP does not account for safe on errors, safe on failed fielder’s choice. • Major League DER in 2007, 0.686.
Calculating Probabilities • Use visiting fielders, so one fielder does not dominate. • Sum total chances and outs for each set of six parameters. Probability = outs/chances. • Smooth against data for all fielders. • If more than 50% of chances are by visitors, visitor data get 100% of weight. Else, visitor data weighted by 2*percent of visitor chances.
Ranking Teams • Count number of balls in play (BIP). • Count number turned into outs (Outs). • Calculate expected number of outs (Exp), ∑p(out|D,T,S,BH,BP,PK) • Calculate DER (Outs/BIP), Expected DER (Exp/BIP) • Rank by Difference or Ratio (DER/Exp DER) • 2007 Team PMR Rankings
Probabilities for Players • Split up DER for a set of parameters by how many outs are started by a fielding position.
Links • Range Charts • PMR on Baseball Musings