Wednesday, March 6, 2013

Quantifying Carrick Felix's Defense

Arizona State, picked to finish 11th in the Pac-12 preseason poll, has been a pleasant surprise this year. Currently they are right on the outside looking in at the bubble, but just about no one thought they would be in this position entering the season. Last month, I received an email from Arizona State's assistant coach Eric Musselman. In the email, he told me to check out Carrick Felix's "amazing" defense this season for the Sun Devils. Since then, he has also been quoted on the same topic in this article. Musselman said of Felix, "He’s got to be one of the top five defenders in all of college basketball." Naturally, I decided to try and quantify Felix's defense to dig deeper.

To look at Felix's defense, I decided to just look at Pac-12 games. Generally, ASU has used Felix to guard a top scorer. Felix's versatility is a tremendous advantage here, as he has guarded point guards, shooting guards, small forwards, and power forwards. I wanted to find conference games where Felix guarded just one player for a full game. Then, I could compare the player he guarded's game stats to season averages to get the "Felix Effect". I realize that this method has some limitations. First, the goal of defense is not solely to stop your man. Instead, teams tend to have a defensive philosophy rooted in help principles. Also, there are many circumstances where players stop guarding their assignment over the course of a game. The two most common are transition plays (where the primary goal is to stop the ball) and switches due to screens. Regardless, I identified nine conference games where I determined that Felix primarily guarded one man for nearly (if not all) of the game. The following is a graph of these nine instances. The head of the player Felix guarded represents that player's season ORtg, while Felix's head represents that player's game ORtg. When Felix's head is higher, it means he was "bad" on defense. When Felix's head is lower, it means he was "good" on defense.


As you can see, Felix started the year out with two great games against Andre Roberson (Colorado) and E.J. Singler (Oregon). The only player to significantly get the best of him in conference play has been Mike Ladd of Washington State. In total, Felix has held six under their average ORtg and three over their average ORtg.

The above table shows Felix's defense in more detail. Negative numbers are a good thing from Felix's perspective (hence the green formatting). On average, Felix has lowered a player's offensive rating by about seven points per 100 possessions. We can also see that although Ladd was very efficient in his game against Arizona State, his usage was lower than normal. A defender's ability to affect three point percentage has been heavily scrutinized, so we should probably take those percentages with a grain of salt. However, I fully agree with the numbers concerning free throw attempts. I thought Felix did a great job of not trying to do too much on defense and avoiding fouls. The numbers do say that Felix has had a tendency of not letting players get to the line as much as they are used to.

I wanted to take a look at Victor Oladipo, who is regarded by many as the best defender in the country. Tom Crean's usage of zone defense, however, complicated matters. I was only able to identify five conference games where Oladipo spent the vast majority of his time on one offensive player. Those games are below:

When watching film, it's easy to tell the difference in defensive style between Felix and Oladipo. The latter is very agressive, ranking 20th in the country in steal percentage and averaging 3.6 fouls per 40 minutes. it's hard to really take anything from this small of a sample size, but I was surprised that offensive players have gone at Oladipo. Ryan Evans was the only player who was used on offense less than normal against Indiana. 

It's no secret that defensive statistics are far behind offensive statistics. One of the biggest talking points at the  MIT Sloan Sports Analytics Conference last weekend was the use of new technology to better measure defense. This is especially true for the college game, where we don't have much beyond blocks and steals. I will be the first to say that the best way to judge a player's defense is to watch film. Clearly, Felix's defensive prowess is easily spotted by watching Arizona State play. My goal was to back up the film with numbers. Although the method has some flaws, I think combined with the eye it can give a better total picture of a player's defensive performance.

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