Amidst all the talk of poor substituting and baffling rotations seen throughout this season, I thought I would look at something Gonzaga did particularly well this season - defend the perimeter.
I wasn't sure where to start until I saw these great posts on perimeter defense on the kenpom blog (a great site, I would highly recommend checking it out if you are looking for a better grasp on CBB stats). To summarize, the numbers suggest that a defense actually has very little control over the opposing team's three-point percentage. This came as a particular surprise to me as that tends to be one of the statistics I have put a fair amount of weight in in judging GU's defensive performance. That being said, it makes complete sense.
3PA%, or the percentage of the opposing team's FG's that are from beyond the arc, is a more useful stat for determining a defenses effectiveness. According to kenpom:
People that are unaware of 3PA% (which is to say nearly everyone) are missing a very telling statistic that explains a lot of how defense works. It’s infinitely more useful than defensive 3P%, anyways. Can coaches use this to their advantage? I’m not sure, except to say that at first glance I think Shulman is crazy for running the system he does. However, I like having him around. The strategic diversity that college hoops offers is part of what make D-I hoops so much more interesting than the NBA to me. I tend to think K, Randy Bennett, and Rick Majerus have it right, but there are national-championship winning coaches (Jim Boeheim and Tubby Smith are two) that run systems that allow a high amount of opponents’ three-point attempts and I’m guessing they have good reasons.
Naturally, I thought about Gonzaga after reading this and decided to calculate a few statistics of my own. Instead of going through the headache of looking at every season over the last decade, I just decided to compare two seasons that appeared, at least at first glimpse, to be polar opposites with regards to the perimeter: the 11-12 Zags, and the 10-11 Zags. It isn't the most statistically honest way to assess Mark Few's defenses over the years, but as far as the fan bitch-o-meter goes, last year definitely showed a peak in complaints about perimeter defense, whereas this years bitch-o-meter clearly goes to substitutions and rotation issues.
*Disclaimer*: I am not a statistician, and calculated a few of these numbers with the help of a few Fat Tire's, so I may have made some mistakes, but the outcome was interesting anyway:
First, the 10-11 season:
The Zags allowed opponents to shoot 36.5% from beyond the arc, with a 3PA% of 35.5%.
The 11-12 Zags allowed opponents to shoot 31% from behind the arc, with opponents 3PA% being around 34%.
This trend would hold consistent with kenpom's data and suggest the Zags really did play better perimeter D (vs. just getting lucky and having people miss). Not only did the 11-12 Zags allow fewer 3PA, but they likely forced opponents into worse looks from beyond the arc and closed out on shooters more effectively, partially explaining the decrease in 3P%.
I am of the mind that most of this was due to the influence of GBJ and Edi on the perimeter, and partially due to Sacre's ability to switch out top and cover guards. Regardless of the cause, I think it was encouraging to see Few put an emphasis on the perimeter to plug up a chronically leaky hole in our D.
I don't really think there is any debate about this year's D being better than last, but now I'm wondering: How much of these numbers can be accounted for by our SOS? How much for our favorable number of home games? And how much was a true shift or adjustment from the coaching staff to better strategies and/or more buy in on D from the players? And with Rob leaving, how will our defense, specifically on the perimeter, fare next year?
Just thought I would share these thoughts, please debate charitably. Extra points for use of statistics in your arguments, and if you have to insult another member to get your point across, extra points if you at least make it creative.