January 27, 2012 - by David Hess
Indiana Freshman Cody Zeller No Match For Wisconsin Forwards [Defensive Charting]
posted in NCAA Basketball
Because this game was the only matchup this Wednesday or Thursday between two ranked teams, and because the score made it look like a defensive battle, I put it under the defensive charting microscope.
5 Biggest Takeaways From Charting The Game
The actual numbers are at the bottom of the post for those who are interested. But they’re worth nothing if they don’t lead to insights, so here’s the most important part — what I learned from reviewing the defensive tape, that I might have missed if I was watching as a casual fan.
1) Mike Bruesewitz Put This Game Away For The Badgers Down The Stretch By Outplaying Cody Zeller At Both Ends Of The Floor. With under a minute left, Wisconsin was up by three, but the Hoosiers had the ball with a chance to tie or move within one. Indiana fed the ball to Zeller, who was isolated down low against Bruesewitz. The Wisconsin forward played solid positional defense, got his arms up, and kept his feet on the ground to avoid a foul. Zeller couldn’t power through or elevate over Bruesewitz, and his shot fell well short and was rebounded by Jordan Taylor.
Taylor dribbled down the court, burned most of the clock, then missed a contested shot which was rebounded by none other than Mike Bruesewitz, who knocked Zeller to the ground on his way to the boards. Bruesewitz was fouled and knocked down both free throws, essentially putting the game on ice.
2) Jordan Taylor Got Abused In The First Ten Minutes. Taylor allowed 4 made field goals in the first ten minutes, while forcing zero misses. Twice he went under a screen and ended up losing his man, and twice he simply was beaten to the lane off the dribble. He most certainly did not look like the Big Ten All-Defensive Team player he is known as. At that point, Wisconsin started switching on most perimeter screens, which helped Taylor’s defense considerably, but led to occasional mismatches that Indiana attempted to exploit.
3) Wisconsin’s Jared Berggren Was A Shot Blocking And Shot Altering Machine. Berggren was credited in the box score with 5 blocks in only 23 minutes, but even that underestimates his impact in this game. He set the tone in the opening minutes by scoring early when he was one-on-one against Cody Zeller, and blocking Zeller multiple times on a single sequence later. Without a couple of borderline foul calls, he would have ended up as the best rated defender on the Badgers, and likely would have racked up even more blocks in his increased playing time.
4) Indiana’s Christian Watford and Jordan Hulls Can Do Much More Than Just Hit Threes. The two players are both shooting an amazing 49% from three point range, which might lead casual fans to assume they are prototypical long range specialists. But Watford may have been the best defender on the floor for Indiana. He did an excellent job cutting off passing lanes, and used his length to pester Badger shooters, forcing 5 forced misses and one turnover, against only 1.5 made shots and 0 free throws allowed.
Hulls, meanwhile, was the team’s leading defensive rebounder and helped hold Wisconsin’s guards to a combined 14 of 39 (36%) from the floor (I’m including Ryan Evans as a guard here.)
5) Good Box Outs Led To A Lot Of Defensive Rebounds By Guards. The three leading defensive rebounders in this game were Jordan Hulls, Jordan Taylor, and Ryan Evans — two guards and a guard forward. Because of this, the big men in this game are slightly undervalued by their raw defensive ratings (which include defensive rebounding values). Berggren in particular had several plays where he was busy swatting the shot of an Indiana player, and had to rely on a teammate for a rebound.
A Quick Review Of Defensive Charting
OK, now here’s where we start to get technical. If you’re familiar with this individual defensive charting series, and just want to see the data, you can go ahead and skip straight to the box score. For everyone else, here’s a brief summary of what’s below.
Traditional player box scores have very little in the way of defensive record keeping, with only blocks and steals tallied. In order to get more detailed info, and to find out who actually does a good job of the main goal of defense — preventing the opponent from scoring points – it’s necessary to do the work yourself.
That means poring over game film (thank you for existing, ESPN3 and DVR technology) to chart the responsible defender(s) for any action by the offense that shows up in a box score.
For a thorough review of the process itself, you can check out this old defensive charting post. But the main idea is that every shot, turnover, rebound, and free throw by the offense gets credited to an individual defender (if possible). Then, we can use that data to construct a Defensive Rating that is analogous to the Offensive Rating that has recently become popular in basketball analysis.
Defensive Box Score: Indiana Hoosiers at Wisconsin Badgers
Here are the numbers themselves, for those who are curious. Definitions are below.
Defensive Charting Definitions
These numbers come from four sources.
Taken from the traditional box score:
- Min – Minutes played
- DREB – Defensive REBounds
Tracked directly by the charter:
- FM – Forced field goal Miss – when a defender forces an offensive player to miss a shot from the field. Oliver separates FM from Blocks, but we’ve lumped them together here.
- FTO – Forced TurnOver – when a defender forces an offensive player to turn the ball over. Again, Oliver separates out Steals, but we’ve combined them. One thing to note here is that a player who draws an offensive foul is always credited with a FTO, even if it’s just a moving screen.
- FFTA – Forced missed Free Throw Attempt – missed foul shots resulting from a defender’s foul
- DFGM – allowed Defensive Field Goal Made – when a defender’s error or poor play leads to an offensive player scoring a field goal (intentional fouls at end of game excluded)
- DFTM – allowed Free Throw Made – made free throws resulting from a defender’s foul (intentional fouls at end of game excluded)
- Stops – the credit a defensive player gets for actions that contributed to ending an opponent possession. This isn’t as simple as adding FM + FTO + 0.4*FFTA, because the credit for a missed shot has to be shared with the defensive player who rebounds it. The formula is more complex than you might think, and includes a sliding weight for FM vs. DREB, based on how difficult those actions seem to be in each particular game. For full details, see Appendix 3 of Basketball On Paper.
- ScPos – Scoring Possessions allowed by a player. This is essentially just DFGM plus a FT-related factor. Again, see Basketball On Paper for the full formula.
- DPoss – [Stops + ScPos] – total Defensive Possessions that were credited to (or blamed on) a player.
- Stop% – Stop Percentage — [Stops/DPoss] – the fraction of an individual player’s credited defensive possessions that ended with zero points. Essentially the inverse of offensive Floor%.
- %DPoss – Defensive Possession Percentage — [(Min/40)*DPoss/TeamDefensivePossessions] (for a non-OT game) – the percentage of team defensive possessions faced by an individual defender. Analogous to %Poss on offense.
- DRtg — Defensive Rating – [(1–%DPoss)*TeamDRtg + %DPoss*(100*TeamDefPtsPerScPoss*(1-Stop%))] – individual Defensive Rating. Gives a player credit for stops and scoring possessions he was directly involved in, then assumes a nebulous team-average performance in the other possessions. This is the analog of offensive rating.
Chart A Game Yourself! Other People Are Doing It.
We’re working to develop a new section of the site that highlights all the defensive charting efforts in the stat community. The latest example comes courtesy of Tommy D on Duke Hoops Blog, who charted defense for Duke’s game against Western Michigan. We’d love for anybody interested in charting to shoot us an email. We’ll provide an Excel template and some tips to get you started, and you are welcome to publish the results on your own blog or in a guest post here at TeamRankings.