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Tuesday, September 20, 2005

Individual Stats Primer

Since there will be more discussion of individual stats on this site this season, I thought I’d throw together a post to let people know what values of each are exceptional. These are the measures I refer to on a regular basis. I’ll add to and adjust this document as events warrant.

Percentage of possible minutes played (%Min): Self explanatory, I think. La Salle’s Steven Smith (97.3%) led all D1 players in 2005. He missed just 32 of the 1,185 minutes that the Explorers played. Wyoming point guard Jay Straight (96.9%) was second, including a Ripken-esque nine consecutive games without a rest. Few players exceed 90%.

Offensive rating (ORtg): A measure of personal offensive efficiency developed by Dean Oliver. The formula is very complicated, but accurate. For a detailed explanation, buy Basketball on Paper. Anything over 110 is good, and 120 is excellent for a player that is the workhorse on his team. The best I saw from last season was Utah State’s Spencer Nelson at 133.

Percentage of possessions used (%Poss): A measure of personal possessions used while the player is on the court. Simply assigns credit or blame to a player when his actions end a possession, either by missing a shot that isn’t rebounded by the offense or committing a turnover. 20% is average, and 25% indicates a go-to guy. 15% is a player with a limited role in the offense. Higher values do not indicate a player is better, merely that he is more involved in the offense. It’s almost impossible to get to 30% in the college game, although Vermont’s Taylor Coppenrath did so in 2004 and 2005. It is difficult to combine high possession usage with high offensive rating.

Percentage of shots taken (%Shots): This is the percentage of a team’s shots taken, while the player is on the court. This is a pretty good proxy for %Poss, and significantly easier to calculate. It is PlayerFGA / (%Min * TeamFGA).

Effective field goal percentage (eFG%): Same as regular field goal percentage, except that made three-pointers are appropriately given 50% more credit. The top ten in this category with at least 300 FGA from the 2005 season, with players in bold returning in 2006: 

 1 Salim Stoudamire  Arizona     64.8
 2 Jaycee Carroll    Utah St.    64.2
 3 John Reimold      Bowl Green  63.6
 4 Dee Brown         Illinois    63.6
 5 Josh Almanson     Bowl Green  63.2
 6 Andrew Bogut      Utah        63.0
 7 Eric Williams     Wake Forest 63.0
 8 Daniel Kickert    St.Mary's   62.8
 9 Michael Harris    Rice        61.6
10 Seamus Boxley     Portland St 61.1

It’s mostly players that shoot a lot of threes and shoot them well, but there are some post players that sneak in also.

Offensive rebounding percentage (OR%): This is the percentage of possible offensive rebounds a player gets: 

PlayerOR / [%Min * (Team OR + Opp. DR)]

The denominator is scaled based on the percentage of a team’s minutes played by the player. Anything over 10% is good. Sean May of North Carolina was the best I saw for the 2005 season at 16.7%.

Defensive rebounding percentage (DR%): This is the percentage of possible defensive rebounds a player gets: 

PlayerDR / [%Min * (Team DR + Opp. OR)]

Anything over 20% is good. Bogut was the best I discovered for the 2005 season at 31.0%.

It is generally believed that offensive rebounds are more attributable to individual effort than defensive rebounds. Due to its relative rarity, an offensive rebound is considered more valuable than a defensive rebound.

FT Rate: Free throw rate is calculated by 100*FTA/FGA. This measures a player’s ability to get the line using the number of free throws shot per 100 field goal attempts. Players that shoot a lot of free throws tend to be efficient scorers, so a high free throw rate is a good thing unless the player is horrible from the line. Anything over 50 is good, and 70 is excellent. Dwayne Jones (109.3) of Saint Joseph’s was the only player in 2005 to exceed 100 in this category among players with at least 200 FGAs. Jones shot only 54% from the line, so all those trips to the line didn’t hurt the opposition much. The oft-injured Jason Fraser of Villanova deserves mention for posting 115 FTAs with 90 FGAs for a free throw rate of 127.8. Below are the top ten players in FTRate with at least 200 FGAs. Only two return in 2006. 

 1 Dwayne Jones      St. Joseph's 109.3
 2 Ellis Myles       Louisville    98.8
 3 Steven Thomas     Texas Arl.    91.9
 4 Jamar Howard      Wichita St.   91.4
 5 Jason Maxiell     Cincinnati    90.4
 6 Ronny Turiaf      Gonzaga       83.8
 7 Blake Hamilton    Monmouth      83.2
 8 Ike Diogu         Arizona St.   78.1
 9 Chad McKnight     Morehead St.  77.6
10 John Bowler       E. Michigan   77.6

Turnover Rate (TORate): This is the percentage of personal possessions used on turnovers. It is highly dependent on context, but anything below 15% is great. Average in 2005 was around 20%. Point guards are typically in the 20-25% range due to the nature of their position. Players that do little passing or dribbling will have an artificially deflated TO%.

Assist Rate (ARate): This is assists divided by the field goals made by the player’s teammates while he is on the court. [Changed 4/9/06]

Block Percentage (%Blocks): This is the percentage of opponents’ two-point shots that are blocked by the player while he is on the court. It is computed by Blocks/(%Min * Opponents’ two-point attempts). Anything greater than 8% is very good.

Steal Percentage (%Stls): This is the percentage of possessions that a player records a steal shile he is on the court. It is computed by Steals/(%Min * Team Possessions). Anything greater than 5% is very good.

Posted on 09/20 at 11:20 PM
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Monday, August 01, 2005

Points Distribution

The points distribution page illustrates where a team’s (and their opponents’wink offense in coming from. The numbers in each column indicate the percentage of points scored (or allowed) by each type of shot. Keep in mind that the numbers on this page do not say anything about the quality of a team’s offense or defense. The data provides another piece of the puzzle of how each team plays offense or defense.

Posted on 08/01 at 07:27 PM
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Four Factors

The offensive and defensive summary pages are based on Dean Oliver’s four factors concept. You can read Dean’s more detailed explanation of the four factors here. Essentially, the four factors are the building blocks to the efficiency formula.

Efficiency data gives you an idea of the quality of a team’s offense or defense, but the four factors tell you why a team is good or bad when they have or don’t have the ball. Here’s a breakdown of how each statistic on this page is calculated…

Effective field goal percentage is like regular field goal percentage except that it gives 50% more credit for made three-pointers. 

eFG%  = (.5*3FGM + FGM) / FGA

Turnover percentage is a pace-independent measure of ball security. 

TO% = TO / Possessions

Offensive rebounding percentage is a measure of the possible rebounds that are gathered by the offense. 

OR% = OR / (OR + DRopp)

Keep in mind that rebounding percentage is computed from box score data which does not contain team rebounds. Therefore, the figures shown here may differ slightly from calculations made on the rebounding totals provided by a school.

Finally, free throw rate captures a team’s ability to score from the line. 

FTRateoff = FTM / FGA
FTRatedef = FTA / FGA

Defensive FTRate uses FTA in the numerator since the defense has little control on the percentage of free throw attempts made by the opposition.

In Dean’s piece, he mentions the relative importance of each factor. In the NBA, eFG% is easily the most important factor, followed by TO%, OR%, and FTRate. A “RoboScout"-type analysis of games from the 2005 season shows that the importance of each factor is similar in college, with free throw rate being slightly more important in the college game, but still taking a back seat to offensive rebounding. Each team is different though. For instance, Gonzaga’s free throw rate was the second most important contributor to their offensive success. For Michigan State, offensive rebounding ranked second.

Posted on 08/01 at 06:54 PM
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