Team Defensive Efficiency

Defensive Rating Framework

Team Defensive Rating (DRtg) measures points allowed per 100 possessions, providing the fundamental gauge of defensive quality. League-average DRtg typically falls between 108-112, with elite defenses achieving ratings in the low 100s and poor defenses exceeding 115. Unlike offense where efficiency is constrained by shooting ability, defense can theoretically prevent nearly all scoring through perfect execution.

Defensive Four Factors

The defensive Four Factors mirror offense: opponent eFG% (forcing difficult shots), opponent turnover rate (generating turnovers), defensive rebounding rate (ending possessions), and opponent free throw rate (avoiding fouls). Elite defenses typically excel at limiting opponent shooting efficiency while maintaining solid rebounding and avoiding unnecessary fouling.

Rim Protection vs. Perimeter Defense

Teams must allocate defensive resources between protecting the rim and contesting perimeter shots. Some schemes prioritize rim protection, conceding some three-point attempts; others emphasize three-point contest at cost of some rim access. Understanding this tradeoff helps interpret team defensive performance and identify scheme-specific strengths and weaknesses.

Transition vs. Half-Court Defense

def analyze_defensive_situations(play_data):
    """Separate transition and half-court defense"""
    transition_plays = play_data[play_data['TRANSITION'] == True]
    halfcourt_plays = play_data[play_data['TRANSITION'] == False]

    trans_ppp = transition_plays['PTS'].sum() / len(transition_plays)
    halfcourt_ppp = halfcourt_plays['PTS'].sum() / len(halfcourt_plays)

    return {
        'transition_defense': round(trans_ppp, 2),
        'halfcourt_defense': round(halfcourt_ppp, 2),
        'improvement_area': 'transition' if trans_ppp > halfcourt_ppp else 'halfcourt'
    }

Defensive Consistency

Beyond average defensive efficiency, consistency matters. Teams with high defensive variance may perform well on average but periodically allow explosive scoring runs. Consistent defenses maintain pressure possession after possession, grinding down opponents rather than trading runs.

Implementation in R

# Calculate team defensive metrics
library(tidyverse)

calculate_team_defense <- function(team_stats) {
  team_stats %>%
    mutate(
      # Defensive Rating
      opp_possessions = opp_fga + 0.44 * opp_fta - opp_oreb + opp_tov,
      def_rtg = round(opp_pts / opp_possessions * 100, 1),

      # Defensive Four Factors
      opp_efg_pct = round((opp_fgm + 0.5 * opp_fg3m) / opp_fga * 100, 1),
      forced_tov_pct = round(opp_tov / opp_possessions * 100, 1),
      drb_pct = round(dreb / (dreb + opp_oreb) * 100, 1),
      opp_ft_rate = round(opp_ftm / opp_fga * 100, 1)
    ) %>%
    arrange(def_rtg)
}

team_stats <- read_csv("team_stats.csv")
team_defense <- calculate_team_defense(team_stats)

# Top defenses
top_defenses <- team_defense %>%
  select(team_name, def_rtg, opp_efg_pct, forced_tov_pct, drb_pct) %>%
  head(10)

print(top_defenses)

Implementation in R

# Calculate team defensive metrics
library(tidyverse)

calculate_team_defense <- function(team_stats) {
  team_stats %>%
    mutate(
      # Defensive Rating
      opp_possessions = opp_fga + 0.44 * opp_fta - opp_oreb + opp_tov,
      def_rtg = round(opp_pts / opp_possessions * 100, 1),

      # Defensive Four Factors
      opp_efg_pct = round((opp_fgm + 0.5 * opp_fg3m) / opp_fga * 100, 1),
      forced_tov_pct = round(opp_tov / opp_possessions * 100, 1),
      drb_pct = round(dreb / (dreb + opp_oreb) * 100, 1),
      opp_ft_rate = round(opp_ftm / opp_fga * 100, 1)
    ) %>%
    arrange(def_rtg)
}

team_stats <- read_csv("team_stats.csv")
team_defense <- calculate_team_defense(team_stats)

# Top defenses
top_defenses <- team_defense %>%
  select(team_name, def_rtg, opp_efg_pct, forced_tov_pct, drb_pct) %>%
  head(10)

print(top_defenses)