Why is Jamal Murray’s offensive rating 103 at Basketball-Reference.com but 109.1 at NBA.com/stats? Explained.

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A few days ago I was perusing the data for Jamal Murray at NBA.com/stats, and noticed that his offensive rating was fifth in the NBA among all qualified bench guards, significant not only since it’s a high ranking for a rookie, but perhaps even more notably due to whose company he was in the midst of:

The Blue Arrow’s offensive rating of 109.1 (the 109.4 in my initial tweet was a typo) was fifth among bench guards, after Andre Iguodala, Eric Gordon, Patty Mills, and Manu Ginobli. Coming in next at sixth and seventh were Joe Johnson and Lou Williams. It’s a feather in Murray’s cap for him to be so solidly in the mix of this crew of veterans, all of whom have eight or more years of experience in the NBA, and play for some of the league’s best teams (as evidenced by the fact they have all advanced to their respective conference semi-finals in the playoffs).

Wanting to explore Murray’s standout offensive rating in a little more depth, I turned to Basketball-Reference.com, intending to search for a historical perspective on how many  past players (qualified with a sufficient number of games and minutes) had likewise finished their rookie campaigns with an offensive rating of 109 or higher.

The only problem was, when I looked up Jamal’s page at Basketball-Reference, they had his offensive ratingg listed as 103. I wrinkled my brow, scratched my head, and tweeted about my puzzling find:

I had noticed in the past that there had sometimes been this sort of discrepancy, but I had always chalked it up to the two sites perhaps having slightly different formulas, and, if memory serves (and it might not), this was the first time the difference was so big as to really jump out at me.

For one reason or another, probably just because I got sidetracked, I didn’t pursue the matter any further, and I expected it would likely go unresolved.

But just now I had the pleasant surprise of getting a very helpful reply from Basketball-Reference which clears the mystery up completely:

So there you have it. In basic terms, offensive rating at Basketball-Reference is an individual production stat, while the metric of the same name at NBA.com/stats is essentially a measure of team production when the player is on the court.

So in Murray’s case, the Nuggets as a whole scored 109.1 points per 100 possessions while he was on court, but Jamal himself individually produced 103 points per 100 possessions during his playing time.

Clear enough, right? Two different stats, measuring different things, but both have ended up bearing the same name. (I didn’t ask, but presumably the same difference will be found between defensive ratings at the two sites as well.)

What is less clear, to me at least, is the immensely complicated formula, which is quite a few levels above my pay grade, that Basketball-Reference uses to calculate a player’s offensive rating. For those of you who wish to brave those waters, the formula can be found here.

Many thanks to Basketball-Reference for claring up this matter, which surely would have stuck in my craw for a good long time if they hadn’t shed light on its resolution. Much appreciated!

 

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