Home Chance

home_chance.rb

# the home team's win chance for a normal team not at a neutral field
def home_chance_normal(sim_context,away_team_arg,home_team_arg)
  # away team dvoa, minus 5% if it's the divisional round
  away = sim_context.dvoa(away_team_arg) - home_extra_bonus.to_f
  
  # home team dvoa, capped at 40%
  home = [0.40,sim_context.dvoa(home_team_arg)].min

  # min_max(-0.35..0.35) restricts the value to between -35% and 35%
  # abs_exp(2) squares it and returns the absolute value
  # home_cold_bonus adds 0.0957 if a cold weather team hosts a warm weather team in week 13 or later
  res = 0.606 
      - away*0.637 
      + home*0.868 
      + home.min_max(-0.35..0.35).abs_exp(2)*-1.414 
      + home_cold_bonus(sim_context)
  
  res.min_max(0.05..0.95)
end

# handles the special cases (mostly neutral field)
# calls home_chance_normal for almost all games
def home_chance(sim_context)
  if home_super_bowl?
    home_super_bowl_chance(sim_context)
  elsif neutral_field?
    # for a neutral field game, get the home win% if we pretend that each team is home
    # then average them
    regular_chance = home_chance_normal(sim_context,away_team,home_team)
    reverse_chance = 1.0-home_chance_normal(sim_context,home_team,away_team)
    res = [regular_chance,reverse_chance]
    res.sum / 2.0
  else
    home_chance_normal(sim_context,away_team,home_team)
  end
end