Tobacco Road Report

In a previous post, which can be found here, we provided rationale for the use of tempo-free statistics and detailed how to use the information provided in the box score to quickly estimate the number of possessions in a typical college basketball game. In this edition of VITAL STATS, we detail how we use tempo-free statistics to analyze how efficient teams are on the offensive end of the court.

As a reference point, we need to define what we mean by offensive efficiency. Recall that the staff of TRR is more interested in team statistics and not individual statistics. As the old saying goes, “college basketball has more to do about the name on the front of the jersey than it does about the name on the back.” That may be less true today than before, but we still think it’s true. It’s not important who gets the stats, as long as someone on the team does.

By offensive efficiency we mean how well a team protects the ball, how well the offense generates scoring opportunities, and how well the team converts on these opportunities. The efficiency of an offense can be assessed through the calculation of six simple statistics. We’ll use the box score of the North Carolina’s 98-89 victory over Ohio State on November 29 as an example as we go. We computed 78 possessions in this fast-paced game.

Effective Field Goal Percentage. In the old days (pre-1987 for you young-uns), calculating field goal percentage was enough. Since every shot was a 2 point shot, dividing field goals made by field goals attempted provided a realistic comparison between teams regarding who was more accurate from the field.

With the advent of the three-point shot and its widespread adoption by nearly every offense, the traditional field goal percentage calculation isn’t enough. As my college coach used to say, shooting 33 percent from the three-point line generates as much offense as shooting 50 percent from two point territory.

In other words, shooting 3 of 6 on two-point shots yields six points, the same as can be had by shooting 2 of 6 from three on the same number of possessions. Effective field goal percentage equates these efforts by giving a higher weight to made three point shots since they are worth 50 percent more than a 2 point shots, and is computed as

Effective field goal percentage (EFG) = (Total FGM + 0.5*3 point FGM)/(Total FGA)

In our example above, the team that shoots 2-6 from three would be awarded an EFG of 50 percent, the same as if it shot 3-6 from two.

The Tar Heels are credited with shooting 34 of 64 from the field for a percentage of 53 percent. An excellent effort, no doubt, but one that doesn’t fully recognize the 8-18 shooting on three pointers. This makes an effective field goal percentage for the Tar Heels of (34 + 0.5*8)/64 = 59 percent…even better.

Assist Percentage. Good teams generate shots through a variety of measures. Sometimes its pure athletic ability and one-on-one effort. But most of the time it’s through a team effort of passing, picks, good cuts, and a made basket. Therefore, the number of assists a team is credited with is a good indicator of the team effort as opposed to the individual effort. Good team effort can overcome an off-night by any one individual player. Assist percentage is calculated as

Assist Percentage = Total Assists / Total Team Possessions

The Tar Heels were credited with 19 assists, or an assist on 25 percent of its possessions.

Turnover Percentage. You can’t score without the ball. Too many turnovers equal missed opportunities. This one is simple. Just take the total number of turnovers and divide by total team possessions.

Turnover Percentage = Total Turnovers / Total Team Possessions

The Tar Heels only had 11 turnovers in this game, meaning that they turned the ball over on only 14 percent of their possessions. Nearly the 2-1 assist-to-turnover ratio that teams covet.

Free Throw Proficiency. Good offenses that generate good shots mean a lot of free throw attempts. Pile up the fouls on the opponent and score points while doing so. To get an idea of how proficient the offense is at generating made foul shots relative to field goals, divide the number of free throws made by the number of field goal attempts.

Free Throw Proficiency = FTM / FGA

Carolina went to the line 34 times, converting on 22 attempts. This means a free throw proficiency of 22 / 78 = 34 percent. That’s not great, and if the Tar Heels converted on more of their attempts, the result would have been much better. Still, Carolina got to the line and this helped win the game in the end.

Offensive Rebounding Percentage. Every team has off-nights offensively and it can really be a problem when your best shooters are drawing iron like it’s going out of style. The better teams are those that can hit the glass and gather the misses for offensive put-backs.

Every missed shot is an opportunity for both teams—for the defense to conclude their effort and for the offense to continue their possession—so we need to know who’s doing the better effort. How to know? Compute the percent of times the offense grabs an offense rebound relative to how often the defense gathers the defensive rebounds.

Offensive Rebounding Percentage = Team ORebs / (Team ORebs + Opponent DRebs)

Note that we’re not simply counting the number of offensive rebounds. The number of offensive rebounds is influenced by two things, the number of possessions in the game (e.g. tempo) and how well the team shoots. Instead, we’re computing how likely it is for the offense to continue the possession by hitting the glass.

Carolina out rebounded the Buckeyes 38-25 and the absence of Oden was big in this regard. The Tar Heels grabbed 14 offensive rebounds versus 18 defensive rebounds by the Buckeyes. Translation? Carolina grabbed offensive rebounds on 14 / (14 + 18) = 44 percent of its offensive rebounding opportunities. A stellar number considering good offensive teams will hit 40 percent in this category.

Points Per Possession. In the end, the combination of all these factors—shooting well, creating assists, minimizing turnovers, getting to the free throw line, and hitting the offensive glass—will make the team productive offensively. Efficient teams turn possessions into points.

Points Per Possession (PPP) = Total Team Points / Total Team Possessions

For Carolina, points per possession was 98 / 78 = 1.27. Excellent offensive efficiency resulted in maximizing points on every opportunity. That’s an outstanding number considering the pace of the game, the opponent, the early-season emotion, and the number of freshman getting significant playing time.

So that’s it for our second edition of tempo-free stats and our primer on offensive efficiency. We think they provide an excellent base to assess the efficiency of any offence regardless of pace and offensive style. In the end, offense is about maximizing every opportunity to generate a team win.

Come back soon to see our tempo-free measures for defensive efficiency. Teams that register high on both scales are teams to watch in March.