Friday, April 13, 2012

Video Charting The Swing Offense Of The Wisconsin Badgers | Stat Geek Idol

The following is the second (Sweet 16) post I wrote for TeamRankings' Stat Geek Idol. For more information on the competition click here.

The Wisconsin Badgers, led by Coach Bo Ryan, are a familiar topic of discussion for stat geeks.
The foundation of advanced statistics in basketball is tempo free. That is, numbers that are not influenced by the pace a team plays at. The Badgers are of course known for their slow pace. Without looking at Wisconsin on a per possession basis, you cannot compare them to teams that play faster.
To analyze Bo Ryan’s Swing Offense I watched each Wisconsin possession versus Vanderbilt in the Round of 32 in slow motion and charted categories such as: number of passes, shot location, defender proximity, number of dribbles the shooter takes, time of possession, and more.

What Is The Swing Offense?

Bo Ryan has become famous for his Swing Offense by winning at every level he has coached.
The offense’s formation is four out one in. By putting four guys spread out along the three point line, the one post man has room to operate. Ryan has explained in his DVD that he expects all of his players to be able to play in the post (not just big men). For example, this season 6’6” swingman Ryan Evans gets a lot of post touches.
The basic continuity of the offense is a flex screen (guy cuts across the lane for a potential layup) and a UCLA cut (guy from top of key cuts towards hoop) after the ball is swung to the other side.
However, the Badgers offense is not nearly as simple as this. Wisconsin runs many different quick hitter types back screens, ball screens, and dribble hand offs during each possession. The perceived slowness of the offense is in fact very real.
In the last five years, Wisconsin’s national rank in adjusted tempo has been:
2012: #344
2011: #344
2010: #340
2009: #334
2008: #318
The other qualities of a Bo Ryan offense, especially in recent years, have been shooting the three ball well, shooting the three ball often, and (most importantly) taking care of the basketball. The Badgers do not rebound the ball well on offense (instead focusing on getting back on defense) and do not get to the foul line, but their shooting and ball control make up for it.

Video Charting The Badgers

The initial premise behind my idea to video chart the recent Vanderbilt game was to measure the impact of being patient in Wisconsin’s offense. I planned to calculate an expected value of a shot Wisconsin chose to pass up and compare it to the actual points scored at the end of the possession.
Upon watching each possession I realized that not only does Wisconsin not shoot early in the shot clock, but they don’t even really LOOK to shoot early in the shot clock. In fact, I recorded every time the man with the ball looked to score but decided to remain patient.
This is obviously very subjective and it is hard to define exactly what constitutes intent to score, but my results were as follows:
Plays* where exactly 3 potential scoring options were passed up by ball handler: 1/58 (1.7%)
Plays* where exactly 2 potential scoring options were passed up by ball handler: 3/58 (5.2%)
Plays* where exactly 1 potential scoring option was passed up by ball handler: 19/58 (32.8%)
Plays* where the only potential scoring option was at the end of play: 35/58 (60.3%)
*An offensive rebound or foul call, although one possession, counted as two separate plays. The data also excludes the last few minutes of the game when Vandy switched to zone.
It’s not like the ball handler for Wisconsin is looking to score and then making a conscious decision to be patient. Instead, the offense is designed for a lot of movement without the ball. Many ball screens and dribble handoffs are executed, but not with the intent to score. If you just follow the ball on Wisconsin’s possessions, it really looks like they are just using up the shot clock because they can.
Here are the results of the type of scoring option Wisconsin passed up:
Center drives: 6
Baseline drives: 7
Wing drives: 4
Semi-Contested Three: 4
Contested Three: 5
Post-Up: 1
Fastbreak Pull-Out: 2
With four guys basically always positioned outside the three point line, the only time Wisconsin really passes up two point shots is on the drive. Overall, there were nine threes they thought about taking but decided to pass up and 17 drives.

The Results: Shot Selection

The graph on the top left shows that 59% of Wisconsin’s plays versus Vandy had at least four passes. Seven plays consisted of no passes, which is affected by offensive rebound put back. The exception to this is an occasional quick shot from Jordan Taylor.
The next graph shows that 79% of Wisconsin’s plays were at least 11 seconds long. Again, the quick plays can be attributed to offensive rebound put backs or Jordan Taylor. For the most part, Wisconsin plays tend to last between 11 and 25 seconds.
The bottom left table has the most amazing findings to me. 65% of all shots taken by Wisconsin were of the catch and shoot variety. From Sandy Weil’s findings we know that, “There is something beneficial about the catch and shoot, beyond expectations.”
Finally, the last table shows us that Wisconsin took many wing threes. They were also generally efficient on all shots except long twos and the two NBA threes they took.
Next, I looked at the correlation (r-value) between certain variables and points scored on that play. The one key thing to note is that a play that ended with an offensive rebound or foul on the floor was assigned a point value of 1.1 (Wisconsin’s average PPP).
Correlation between:
Time of Possession & Points: +.08
Number of Passes & Points: +.05
Passes/Second & Points: -.06
Number of Dribbles & Points: +.16
Obviously, the sample sizes here are extremely small with many potential factors confounding the data.

The Results: Individual Players

These four players were the most used versus Vandy.
As you can see, Jordan Taylor is playing a different game than the other three. He took seven shots off the dribble and six shots that were contested.
As a comparison, all but one of Bruesewitz’s shots were open catch and shoots. In fact, Evans, Bruesewitz, and Berggren combined for just four contested shots (less than Taylor). Ryan Evans got off to a very hot start, but struggled the rest of the game with turnovers and a few missed shots.
I was expecting a lot of late in possession Jordan Taylor isolation play. There were some, but overall Wisconsin did a good job of taking the correct shot early enough where isolation wasn’t entirely necessary.

Slow Motion Emphasizes Wisconsin’s Movement Off The Ball

Tracking each play of the Round of 32 game was an interesting experience. Unfortunately, I don’t have the data of a more normal team to compare Wisconsin with.
Vanderbilt switched to zone on the 50th possession of the game and definitely bothered Wisconsin. Going forward the Badgers might see more zone.
Watching each possession in slow motion made be appreciate the movement without the ball of the Swing Offense. Coincidentally, Bo Ryan did NOT appear to share this same appreciation at times during the game.

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