Two weeks ago Jeremy Conlin posted the first set of results from an extended project he and I have been working on. The relationships between the Four Factors and efficiency have been fairly well studied and established, however this has usually been done by looking at aggregate, league-wide data across multiple seasons. This helps establish how these statistical categories work together and overlap at a macro level, but we wanted to drill down to the micro.
We grabbed the game logs for each team from last season and calculated offensive and defensive efficiency, as well as the Four Factors and pace for each team in each game. This lets us look at that way these statistics relate to each other on an individual team level, which can often be very different from the league-wide trends. For example, in our first analysis we found that the Memphis Grizzlies, one of the best offensive rebounding teams, actually had a negative correlation between Offensive Rebound Percentage (OREB%) and Offensive Rating (ORTG). Although hitting the offensive glass was a huge strength for the Grizzlies it was a way of covering up for their other offensive holes. The more they were hitting the glass, the more other things weren’t working, and their overall efficiency was suffering.
Today we’re looking at the relationship between Offensive Effective Field Goal Percentage (OeFG%) and Offensive Rating (ORTG), one that we obviously expect to be extremely strong for all teams – you can’t score efficiently if you can’t make shots. The individual team graphs are below.
This next visualization combines all the individual team information into one graph. The height of each bar represents how strong the correlation was between OeFG% and ORTG. The color of each bar represents the team’s ORTG. The width of each bar represents their OeFG%.
As we would expect the relationship between OeFG% and ORTG was extremely strong for all teams, with the 0.715 correlation for the Milwaukee Bucks being the smallest. We do find an interesting cluster of teams near the top – the Spurs, Rockets and Knicks. Everything the Spurs do comes down to precise execution of their system, with the ultimate output being the production of quality shot attempts. It makes total sense for them to be at the top of this list. If their system isn’t working, open shots aren’t being created and the shots that are being created probably aren’t being made. The Spurs didn’t have a focus on attacking the glass or getting to the rim to scaffold that offensive efficiency when shots weren’t being made. Which is understandable because they didn’t often hit that roadblock.
The Knicks and Rockets are also interesting because they finished first and second in three-point attempts last season, separated from the third team in the league by nearly 300 attempts. Both teams often played smaller lineups and opted to go with a spread attack. The Rockets in particular, with their focus on nothing but three-pointers and shots at the rim, put all their offensive eggs in the shot-making basket. Three-pointers are a tool to buoy offensive efficiency and they can really push the boundaries of a team’s OeFG%. However, they also introduce a ton of variance into the offensive equation and making them at a consistent rate becomes even more important when you’re moving shots away from the rim and the free throw line.
At the other end of the spectrum we find two of the most efficient offenses in the league last season, the Heat and the Thunder, with a smaller relationship between OeFG% and ORTG than the league average. With the tremendous individual scoring prowess and athletic gifts of players like LeBron James, Dwyane Wade, Kevin Durant and Russell Westbrook these teams can afford to miss a few shots here and there, making up for it by leveraging turnovers into transition opportunities and piling up trips to the free throw line. It’s also interesting that teams we think of relying heavily on isolations, the Heat and Thunder, but also the Nets, Lakers and Bucks all ended up on the bottom half of this scale, regardless of how efficient their overall offense was.
If anything jumps out at you that I’ve missed, please let us know in the comments. We’ll be back later in the week to look at some more of these team-level relationships.