Offensive and Defensive Rating

One of the first challenges faced when trying to compare 2 basketball teams is to factor in the pace of play for those teams. If you simply looked at totals for points, rebounds, etc. St. Mary’s would seem to be a better team than the Yellow Jackets. Offensive Rating (OR) and Defensive Rating (DR,) are pace-adjusted statistics that give us the number of points scored and allowed by a team per 100 possessions.

We can easily look up the number of points Tech has scored over the season, but how do we calculate the number of possessions without going through the play-by-play of each game with our abacus in hand? With a large enough sample size, this value can be estimated by using some of the simple statistics found in a team’s final box score.

TmPoss = .5 * (FGA + .475 * FTA - ORB + TOV)

This equation will give you the number of possessions that 1 team had in a game or season, to get the total number in a game or season, you will have to add TmPoss to OppPoss, which will be the same equation using the totals for the opponent(s). Note: the constant .475 value is the estimate for the value of a free throw attempt for college basketball only, the value of the constant for NBA calculations is .44.

Now that we have the number of possessions that occurred in a game or season, we can find Tech's OR and DR.

OR = 100/TotPoss * TmPTS

DR = 100/TotPoss * OppPTS

So, now that we have an understanding of where these statistics come from, let's look at GT's OR and DR compared to the rest of the ACC right now.

<table border="1" style="background-color:white;border:1px dotted black;width:25%;border-collapse:collapse;"><tr style="background-color:gainsboro;color:black;"><th>School</th><th>OR</th><th>DR</th><th>Differential</th></tr><tr><td>Duke</td><td>114.5</td><td>88.4</td><td>26.1</td></tr><tr><td>Maryland</td><td>115.7</td><td>89.6</td><td>26.1</td></tr><tr><td>UVA</td><td>105.6</td><td>83.2</td><td>22.4</td></tr><tr><td>GT</td><td>100.6</td><td>83.5</td><td>17.1</td></tr><tr><td>NCSU</td><td>116.9</td><td>100.3</td><td>16.6</td></tr><tr><td>Clemson</td><td>106.5</td><td>89.9</td><td>16.6</td></tr><tr><td>UNC</td><td>107.7</td><td>91.7</td><td>16.0</td></tr><tr><td>Miami</td><td>105.3</td><td>90.6</td><td>14.7</td></tr><tr><td>FSU</td><td>104.4</td><td>95.9</td><td>8.5</td></tr><tr><td>VT</td><td>105.5</td><td>102.7</td><td>2.8</td></tr><tr><td>BC</td><td>105.0</td><td>103.1</td><td>1.9</td></tr><tr><td>Wake</td><td>100.6</td><td>100.0</td><td>0.6</td></tr></table>

As you would think, Duke is tied for first in the ACC when you subtract DR from OR (point difference per 100 possessions.) Tech ranks second in DR and tied for 12th in OR, which also passes the eye test when you watch them play. But when we look at this closely, it still doesn't make total sense, right? After Saturday, we can safely assume Miami should have a better differential than Tech. So, we should probably consider strength of schedule and adjust for that.

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Now that we've gotten through all that, I'd like to introduce myself to the FTRS community. Obviously, my name is David Gagne and I will be writing primarily about basketball. As you can guess from this first post I am very interested in the statistical side of the game. If this piece has a good reaction I plan to continue going through some more advanced basketball metrics in the coming weeks. If you have any questions or would like some sort of statistic explored, let me know in the comments and I'll see what I can find out for you.