Stats Analysis: Offensive Efficiency
This is the first article in a series that will provide statistical evaluations of Stanford Men's Basketball. Much of the work in the series is based on Basketball on Paper by Dean Oliver, now in the Denver Nuggets front office. Others evaluating the NBA in the media include John Hollinger of www.espn.com and Roland Beech of www.82games.com. At the NCAA level, Ken Pomeroy has provided the fundamental efficiency statistics for each Division I team on www.kenpom.com. We will use these analyses on this year's team, but we will first introduce fundamental concepts by looking at the best offenses and defenses in Stanford men's basketball history. Today, we'll look at the best offenses over the last 11 seasons (we'll start with the past 11 seasons and update this article when we finish obtaining stats going back to 1986-87, the first season with the three-pointer). We'll look at defenses later this week.
The building block for evaluating offensive and defensive efficiency is to adjust by possessions or pace of play. In any game, each team alternates possession with its opponent and ends up with approximately equal number of possessions. In 2006-7, the Virgina Military Institute led Division I with 90.7 possessions per 40 minutes and Princeton was last with 53.4 possessions per 40 minutes. As a result, VMI games will be higher scoring than Princeton games, but points per game do not reflect how well teams score and stop other teams given the number of scoring opportunities there are. Efficiency statistics normalize for tempo by evaluating points per possession. Offensive rating is points scored per 100 possessions and defensive rating is points allowed per 100 possessions.
Unfortunately, number of possessions isn't an official statistic so, to be practical, we have to estimate it from the box score. In his nationwide statistics, Ken Pomeroy estimates possessions by the following formula:
Possessions: Field Goals Attempted - Offensive Rebounds + Turnovers + 0.475 x Free Throws Attempted
You can see that made field goals and missed field goals rebounded by the defense will end a possession. Therefore, offensive rebounds are subtracted as they continue possessions. Some commentators will refer to offensive rebounds giving teams "extra" possessions, but that definition is not as helpful because we want each team to have equal numbers of possessions in any game. Turnovers also end possessions. Calculating how many free throw attempts end possessions is not so clear cut. Free throws usually come in pairs, but some come in threes, are after made field goals, are missed front ends, or are for technical fouls which don't necessarily end the possession. Pomeroy estimates that 47.5% of free throw attempts end a possession. There is some disagreement about this multiplier. Oliver uses 40% based on his work in the NBA, but we will use Pomeroy's formula to be able to make comparisons to his NCAA statistics.
With these basics in hand, let's rank the teams by offensive rating (points scored per 100 possessions) for the last 11 years.
|Season||Possessions Per Game||Offensive Rating||Effective FG%||Offensive Rebound Rate||Turnover Rate||Free Throw Rate|
The 2001 team that advanced to the Elite 8 behind Casey Jacobsen, the Collins twins, Mike McDonald, and Ryan Mendez is easily the highest-rated offensive team of the last eleven years. The other numbers in the table show why. Dean Oliver calls these the four factors that make up the efficiency rating, in approximate descending order of importance.
Effective FG% = (Field Goals Made + 0.5 x 3 Pointers Made)/Field Goals Attempted
Shooting is easily the most important factor in offense. This factor accounts for the additional point gained by making a three pointer and the 2000-2001 team took advantage with Jacobsen, McDonald and Mendez all shooting over 40% from behind the arc and the Collins twins combining to shoot 59% from the floor.
Offensive Rebound Rate = Offensive Rebounds/(Offensive Rebounds + Opponents' Defensive Rebounds)
This factor divides offensive rebounds by the number of offensive rebounding opportunities. The often-used rebounding totals and rebounding margins are less useful because they depend on the number of shots missed. If your team misses a lot of shots, it's more likely they will get more offensive rebounds. The other thing rebounding rates do is separate what happens at the offensive and defensive ends of the floor. Offensive rebounds should be compared to opponents' defensive rebounds. Defensive rebounds should be compared to opponents' offensive rebounds. The 2001 team was not one of the stronger offensive rebounding teams even with the Collins twins. The 1998 and 1999 teams with Tim Young and Mark Madsen were very good in this category as was the 2002 team anchored by Curtis Borchardt and half a season of Justin Davis. We have not collected all of the statistics for the Adam Keefe years, but in 1990, his sophomore year, the offensive rebound rate of 41.7% was better than all of the eleven past seasons.
Turnover Rate = Turnovers/100 Possessions
This factor measures the percentage of possessions lost to turnovers. The 2001 team was at the top in this category. The second-best team on this list was the 1997 team with senior point guard Brevin Knight, who was excellent at ball security. Knight's freshman year team in 1994 actually had a lower turnover rate than each of the last eleven years and we will see how the teams from his sophomore and junior years match up when we obtain the remaining data.
Free Throw Rate = Free Throws Made/100 Possessions
This factor measures the ability of the offense to get points from the line. The statistics on kenpom.com use field goal attempts in the divisor, but the ability to get to the line late in the game instead of turning the ball over also seems important. The 2001 team was at the top of this category, along with the 1999 team that was the first to win a Pac-10 championship behind a senior-laden team of Art Lee, Kris Weems, Peter Sauer, and Tim Young.
The table also shows the difference in "tempo" between teams. Knight's 1997 team had the fastest tempo in the last 11 years. This was a very small team with Knight, 6'0" Arthur Lee, and 6'3" Kris Weems in the starting lineup by season's end. (By their senior years, however, Lee would be listed at 6'1" and Weems 6'2"; apparently, they were such good friends that Kris would give Art some of his height!) Knight's freshman year with Dion Cross and Brent Williams was actually played at a faster tempo. The slowest tempo team on the table was the 2006 team with Chris Hernandez, Matt Haryasz, and Dan Grunfeld, but some of the early Mike Montgomery teams may have been slower as our 1990 data shows that team averaging 65.6 possessions per game.
Casey Jacobsen is the common person to the three teams at the top of the table of offensive ratings. At the bottom of the table are the last three years under Coach Trent Johnson. This is mostly related to poor shooting, which is related to not having players approaching Jacobsen's skill level. In 2005-6, effective field goal percentage was in the 47% range and ranked worse than 250th in Division I-A according to kenpom.com as Chris Hernandez was the only good three point shooter over both seasons. Fortunately, the core of this year's team showed an uptick in shooting last year moving up to 178th nationally. The previous two teams missed a lot and did not retrieve many of their misses, barely ranking in the top 150 nationally. Last year's team did a better job of that too, moving into the top 40 nationally. However, offensive improvement was muted last year, because the turnover rate was the highest in the last eleven years and the free throw rate was near the bottom. The turnovers got much attention last year (201st in Division I-A) but the free throws (a disappointing 191st in Division I-A last year) should be a concern too, especially after the grand total of three free throws in the frustrating loss to Siena.
We'll look at defenses next, but using the fundamentals introduced above, we'll follow that by looking at individual player offensive efficiencies. The first example of that will be a look at the year-by-year offensive efficiencies of Stanford point guards and how current point guard Mitch Johnson compares to previous "1s" after their first two seasons on the Farm.
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