What we are calling “Team Defense” is really just a very loose proxy using 2-Period Shots-Against per 60 mins (2pSA/60). Using the first two periods is a fair attempt to remove score effects, or the surrendering of shots while “protecting the lead,” from the shot-based measure. The greater concern is the potential for arenas to vary in the amount they record events. Typically, we offset this by always considering shots-for and against together, as a percentage (2 shots-for, 2 shots-against = 50% shots-for percentage), as arenas that count high or low for one team will almost always count at a similar rate for the opposing team. That said, without having yet tested or adjusted for this in the data below (we plan on doing this in the future), most should be reliable, but some will have arena bias in them.
The data is split 1952-53 to 1992-93 and 1993-94 to 2014-15 for reasons explained in the introduction for historical team comparisons.
The charts below include both cumulative and 20-game moving averages of the measures, as well as league averages and +/- 1 standard deviations from league average for the seasons queried. Personally, for any one season I prefer to show +/- 1 standard deviation in the measure and then the team’s measure in-question, and leave out the league average or anything else that might clutter. But it’s up to you. To choose different seasons and lines, click on the grey “Report” bar, then select “Filter.”
If you’re stumped as to which seasons you should query, you might find our franchise possession and shooting history charts helpful; they depict each franchise’s entire history, and can indicate some of the seasons where drastic changes took place.
P.S. Some of the limits of the display are really just the limits of the embed and WordPress. If you have an Office Online account, you can click on the bottom right icon below any of the graphs to see the data; if you don’t, you can still download the document by clicking the left-most of the icons in the bottom right.
If you need help with learning how to use the graphs, or troubleshooting, or have questions, suggestions, or data requests, please check out our tutorial.