“What does that stat mean?”: Pace & per 100 possession ratings explained
Both of these statements are true:
- The Buffalo Bulls scored 12 more points per game than the Green Bay Phoenix last season.
- The Green Bay Phoenix were better on offense than the Buffalo Bulls.
That doesn’t seem to make sense, right? Our first instinct is that a good offense should score a lot of points, and yet Green Bay finished 162nd in the nation in points scored per game; Green Bay averaged just 66 points a night to Buffalo’s top-25 mark of 78.
To understand how this can be the case, let’s look at how these teams play. Here’s a clip from Green Bay’s first-round matchup against Minnesota in the NCAA Tournament.
On the other hand, here’s a clip from the Bulls’ first-round game versus USF.
What’s important here is not to focus too much on whether the teams scored or not, but the vastly different speeds they play at. Both clips cover about 50 seconds of game time; in the time it takes for Green Bay to conclude just one possession, Buffalo gets through two — and their opponents get a possession too!
If you were to put a number on this evident difference in playing style (and at Her Hoops Stats, we love putting numbers on things), it would be Pace, also known as Possessions Per 40 Minutes. The statistic is pretty self-explanatory, as it measures the number of possessions a team uses in a typical 40-minute game. The end of a possession occurs when the other team gains control of the ball, either via a made shot, rebound or a turnover. If a team misses a shot, gets the offensive rebound, pulls it out, gets fouled, and hits the free throws, that’s considered one possession.
Green Bay ranked in the bottom 10 in the nation with just 64 possessions a game. Buffalo, on the other hand, was in the top 15, getting through nearly 77 possessions a game. To put that difference into perspective, Green Bay would need nearly an extra quarter of basketball (over 7 minutes to be exact) to reach 77 possessions.
These two teams, then, are certainly at the extremes of the nation in the pace department, but there’s a clear, pretty intuitive trend across all of the NCAAW, — the more possessions teams tend to use in a game, the more points they score.
So, Buffalo certainly score more points per game than Green Bay. Does that mean they’re a better offense, though? Or do they just get more scoring chances?
The statistic Points per 100 Possessions (also known as Offensive rating, or ORtg for short) was created for this very reason. With per-possession stats, we can control for the number of opportunities each team had to score. If Green Bay gets 100 possessions and Buffalo gets 100 possessions, who scores more?
Buffalo scored 101 points per 100 possessions last year. That was quite a good mark, and better than 85% of teams. As noted at the top of the story, however, Green Bay was actually even better, scoring more than 102 points per 100 possessions.
We can apply this in a similar manner to the two teams’ defense, by looking at their Points Allowed Per 100 Possessions (Defensive Rating or DRtg). Green Bay retained a significant edge even when pace was accounted for, allowing only 74 points per 100 possessions to Buffalo’s 84. In fact, Green Bay’s mark was 2nd in the nation, behind only UConn.
Finally, we can combine these two statistics into one number that summarises the overall performance of a team. Margin of Victory per 100 Possessions (aka Net Rating) is, quite simply, ORtg minus DRtg — if you played 100 possessions, what was the average number of points you expected to outscore your opponent by (or were outscored by)? Green Bay boasted a Margin per 100 Possessions of nearly 28 points, 4th in the nation and much higher than Buffalo’s 17.
Green Bay isn’t the only team with per-possession numbers at odds with their per-game marks, either. Across the NCAAW, there’s no real relationship between the pace a team plays at and the quality of its offense or defense. There are fast teams with poor offenses, and slow teams with great ones.
So, next time you spot a team that seems to have a low scoring output, don’t be too quick to write off their offensive prowess! Some teams may rack up points by simply playing faster but others, like Green Bay, have found that in some cases it’s slow and steady that wins the race.
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