Tuesday, February 7, 2012

Defensive Charting: Wake Forest

You can see the full story over at Pack Pride. I'm posting this for my own housekeeping purposes.

Here's the key for reference in forthcoming posts:

Taken from the traditional box score:
• Min – Minutes played
• DREB – Defensive Rebounds
Tracked directly by the charter:
• FM – Forced field goal Miss – when a defender forces an offensive player to miss a shot from the field. This includes blocked shots.
• FTO – Forced TurnOver – when a defender forces an offensive player to turn the ball over. This includes steals. One thing to note here is that a player who draws an offensive foul is always credited with a FTO, even if it’s just a moving screen.
• FFTA – Forced missed Free Throw Attempt – missed foul shots resulting from a defender’s foul
• DFGM – allowed Defensive Field Goal Made – when a defender’s error or poor play leads to an offensive player scoring a field goal (intentional fouls at end of game excluded)
• DFTM – allowed Free Throw Made – made free throws resulting from a defender’s foul (intentional fouls at end of game excluded)
Calculated Tallies:
• Stops – the credit a defensive player gets for actions that contributed to ending an opponent possession. This isn’t as simple as adding FM + FTO + 0.4*FFTA, because the credit for a missed shot has to be shared with the defensive player who rebounds it. The formula is more complex than you might think, and includes a sliding weight for FM vs. DREB, based on how difficult those actions seem to be in each particular game.
• ScPos – Scoring Possessions allowed by a player. This is essentially just DFGM plus a FT-related factor.
• DPoss – [Stops + ScPos] – Total Defensive Possessions that were credited to (or blamed on) a player.
Calculated Metrics:
• Stop% – Stop Percentage — [Stops/DPoss] – The fraction of an individual player’s credited defensive possessions that ended with zero points. Essentially the inverse of offensive Floor%.
• %DPoss – Defensive Possession Percentage — the percentage of team defensive possessions faced by an individual defender. Analogous to %Poss on offense.
• DRtg — Defensive Rating – Individual Defensive Rating gives a player credit for stops and scoring possessions he was directly involved in, then assumes a nebulous team-average performance in the other possessions. This is the analog of offensive rating. The lower a player’s DRtg, the better he played defensively.

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