gistfile1.rb

positions = Position.all(:conditions => ["name in (?)", ["wr","rb","te"]])
players = Player.all(:conditions => ["position_id in (?)", positions.map(&:id)])
rec_td_stat_name = StatName.find_by_title("Reception Touchdowns")
rush_td_stat_name = StatName.find_by_title("Rush Touchdowns")
rrtd_stat_name = StatName.find_by_title("Rushing and Receiving Touchdowns")

players.each do |player|
  seasons = player.career_seasons
  seasons.each do |season|    
    stats = []
    [rec_td_stat_name, rush_td_stat_name].each do |stat_name|
      stats << player.career_stats.find_by_season_id_and_stat_name_id(season.id, stat_name).value
    end
    rrtds = player.career_stats.find_by_season_id_and_stat_name_id(season.id, rrtd_stat_name)
    rrts.update_attribute :value, stats.sum
  end
end