Today, we'll take a look at the past five seasons on the defensive side of the ball. As before, the numbers are for the entire season, including nonconference games.
First, the most important number - Adjusted Defensive Efficiency:
Again, each blue dot represents a Big Ten team, and the pink dot is the average of all teams for that season. Remember that, for Defensive Efficiency, a lower number means better defense. That incredibly low dot in 2008 is Wisconsin - the Badgers had the second best defense in the nation last year, behind only the National Champion Kansas Jayhawks (they've earned all that capitalization). In fact, the Big Ten has placed a defense in the top 3 nationally each of the past three seasons (Iowa in 2006, Illinois in 2007).
At the other end of the spectrum, Northwestern in 2008 sported the worst Big Ten defense of this timeframe. As for all those other dots above 100, they belong almost exclusively to Penn State, save for an awful 2004 Ohio State defense. If Penn State is to become anything more than mediocre, their consistently bad defense will have to improve.
Now, Effective FG% Allowed:
The trend here is basically identical to Defensive Efficiency, which makes sense - if you keep your opponents from making shots, you're keeping them from scoring, unless your rebounding is absolutely terrible. The serious outlier here (way up there in the stratosphere) is that 2008 Northwestern squad. We've pegged Northwestern for improvement this season, but they've first got to force their opponents to miss on occasion.
So, if you're forcing opponents to miss, the next step is to prevent them from getting an offensive rebound:
A lower number means better defensive rebounding. The best defensive rebounding team of the era - by a fairly large margin - was Wisconsin in 2005, led by Mike Wilkinson and Zach Morley.
Northwestern owns the three worst seasons of the timeframe, in 2004, 2007, and 2008. So not only is Northwestern allowing opponents to shoot at extremely high percentages, they're also letting those rare misses turn into offensive rebounds. Of course, a shot made available by an offensive rebound is often a high percentage look (a putback or dunk), so maybe Northwestern's eFG% problems are just a sympton of their serious rebounding problem. This season brings some bigger bodies to Evanston, so we may see marked improvement in both areas.
Instead of forcing a miss and rebounding it, there's another path to a successful defensive possession - force a TO:
The conference has remained fairly steady in this regard, although three teams really seperated themselves from the pack in 2008 - Purdue, Minnesota, and Northwestern (the latter two teams had the exact same value, so they appear as one dot in the chart). It's not surprising to see Purdue and Minnesota at the top - they both thrive on pressure defense - but Northwestern is a bit of a shock. This ability to force turnovers may mean that a decent Northwestern defense is just a few rebounds away.
Now, a look at how often Big Ten teams are putting opponents at the foul line:
I don't see a lot of trends here, but it's interesting to note those three dots across the very bottom -of course, that's Wisconsin and the amazing no-foul defense. Except it's not - it's actually Ohio State! Each of the past three seasons, the Buckeyes have finished either 1st or 2nd in the nation at preventing FT attempts. Penn State also surprises here - they were in the top 10 nationally in 2004, 2005, and 2006. The only top 10 finish for Wisconsin occurred in 2008, when they finished 8th.
It certainly seems like the Big Ten has more no-foul teams than you'd expect, especially given the physical reputation of the conference. This is another idea that might demand further investigation.
Next, let's break down the eFG% into its components:
The outliers in 2008 were Michigan and Northwestern. It's really difficult to keep your opponent's eFG% low when you're allowing them to shoot over 38% from downtown. Both teams ranked near the worst in the country - only 24 Division I teams allowed opponents to shoot a higher 3-point percentage than Northwestern, and only one of those teams was from a BCS conference - DePaul. What is it about the windy city that gets visiting teams "heating up" like a rogue programmer in NBA Jam?
There's actually something of a downward trend here. Those dominant teams on the bottom are Iowa (2006), Michigan State (2007), and Wisconsin (2008). That incredibly awful dot in 2008 is - you guessed it - Northwestern. They were the worst BCS-conference team in the nation last year, and were pretty close to being the worst team, period. As I said before, I imagine that their awful defensive rebounding is contributing to this insanely high 2-point FG% - opponents generally convert dunks and putbacks.
A good way to limit your opponent's 2-point FG% is to just get that #$%^ outta here:
The conference has had an uptick of blocked shots the past two seasons - Michigan and Ohio State have led the charge, with 2007 Michigan State chipping in as well. The best shotblockers of the past two seasons are all gone - Greg Oden, Ekpe Udoh, Drew Naymick, Kurt Looby, Kosta Koufos, D.J. White, Othello Hunter... the list goes on and on. It appears that the lane will be a much more hospitable place for offensive players in 2008-09 than it has been for awhile.
Finally, here's that wonderful subset of turnovers, the Steal:
As with turnovers in general, the best steal defenses of 2008 were Purdue, Minnesota, and Northwestern. In fact, those three teams own the 10 best Steal seasons of this timeframe. The overall trend is fairly flat.
Next up, we'll start going team-by-team to look closer at their individual trends.