I acquired all of the Division I team data since 2002, and from that we can observe some fascinating trends and data relationships in the data. This is a multipart series exploring some of that data.
Let's dive into Field Goal Percentage. In the last part of the series I highlighted overall shooting percentages across the last 23 seasons (235,221 games). That's a large statistic, and if we parse out its parts, we can learn more about what is really going on.
3-Point Field Goals
The graph shows the national average in grey, the average for NCAA Tournament teams in green, and UNC's average in blue.
From this we see that national 3-point field goal percentage (3FG%) has essentially hovered in the 34% range for the past 23 seasons. In that period there were 2 big rule changes which pushed the line back: 1 foot beginning with the 2009 season, and 4 inches in 2020. After each of these rule changes we saw a dip of 1-2 percentage points, but there was a quick recovery afterward.
When we look at tournament teams, we see a much more erratic pattern, not following the national average very closely at all up to 2015. While we need more data, it appears that tournament teams have settled in, however, and are shooting roughly .75 to 1.5 percentage points higher than the national average.
UNC's 3FG% history has been erratic, and a cursory glance shows a distinct correlation between high shooting percentages and future NBA guards on the rosters. The current team appears to be exceeding the anticipated tournament level by about 0.5 percentage points, certainly a good sign for this team.
Percent Taken from 3
One important aspect of shooting is how many shots are being taken from this range. From the graph we see that teams were opting much more for 3-pointers annually until the 2019 rule change. Tournament teams used to not be enamored of the shot, but in the mid '10s analytics started showing coaches that they were getting more points per possession on possessions ending with a 3 point attempt than they were inside the arc, so we saw a big strategy change by the field's more savvy coaches.
Roy Williams inherited his big-man-first philosophy from Dean Smith, and as he saw success from great guard play in the Paige/Berry era, his teams opted more from 3 than before. Hubert Davis truly embraced the theory, and his teams have been almost exactly on pace with the rest of the nation in his three seasons as coach.
2-Point Field Goal Percentage
Looking at 2-point Field Goal Percentage (2FG%) tells us more about the effectiveness of the big men and penetration. From this graph we see a distinct rise over time of percentage. Perhaps more teams are taking 3s, pulling guards out of defensive positions in the lane. Perhaps the game is being officiated differently. Nevertheless, we also see a distinct echo by tournament teams of the national average, positioned about 2 percentage points higher.
UNC's performance here is strongly associated with its history of strong big men, though few have made it to play many NBA games. This team, at 50%, is a percentage point below the national average, and probably 3 percentage points below the anticipated tournament team level. This explains why UNC's overall FG% is only at the national average and not at the tournament team average. Despite it's weak link in this area, UNC is still will within 1 standard deviation (3.3%) of both national and tournament benchmarks.
Next up: Effective Field Goal Percentage