Ohio State and the value of hidden possessions

One of the things I await each basketball season is to see which teams I’m going to find intriguing. Besides my own team of course, there tend to be several that I gravitate toward watching as the year progresses. Two of those teams this year are Creighton and Ohio State. Creighton is interesting in the way that a 6’9 man dating a 5’1 woman is interesting. Their offense and defense are complete opposites in form and function (a topic I tackled last week in a film review). Ohio State is intriguing because they contain the ideal balance of jaw dropping athleticism, inspired and fundamental execution, and the perfect dash of completely bone-headed plays. The first two traits make them interesting to watch, while the third makes them fun. On offense this third trait typically manifests itself in one of three ways: 1) Aaron Craft embarking on an offensive maneuver that requires him to be moving at warp speed with a sign advertising that whatever move comes next contained absolutly zero foresight or planning, 2) William Buford jacking shots as if the act alone were worth at least one point for the good guys, or 3) Deshaun Thomas being Deshaun Thomas. On defense this third trait occasionally turns the Buckeyes into a team resembling five guys who just showed up at the gym but who have never actually played together. Occasionally, this can happen for an entire game (Purdue? Hello?) though it typically happens for just 3 or 4 possessions until Thad Matta calls a timeout and reminds his players what the hell they’re supposed to be doing.

This team, as indelible and fun as they may be, has now lost two games in the span of a week. And in these two games neither opponent was able to score a point per possession versus the Buckeyes. Despite that defense Ohio State still lost by a combined 15 points. It was positively Florida State-esque. Though while the offensive struggles are mostly a recent phenomenon, the defensive excellence is not. The Purdue game notwithstanding, Ohio State’s defense is elite and if they can get their offense un-kinked then this will be the most dangerous team in the Tournament not named Kentucky. How do they do it, and how good are they?

Typically, this is where I go to a film review. And Ohio State has plenty of interesting film to digest. But the overall theme of their defense is more intrinsically a numbers game. And so, instead of the film, we turn to the data.

Let’s get the most important statistic out of the way. Ohio State’s defensive efficiency is a ridiculous 81.4, meaning they allow (adjusted for strength of opponent) a measly 0.814 points per possession, which is the best in the country. In fact it’s not even close. The number two team (Michigan State) allows 0.841, or 3.3% more. Considering Ohio State has played almost 1,850 possessions, that 3.3% works out to about 61 points better than the next closest defense. Since adjusted efficiency data became available (2002-03) this figure (81.4) is the lowest. Here are the top ten:

team year dEff
1 Ohio State 2012 81.4
2 Kansas 2007 82.2
3 Memphis 2009 82.5
t4 Kansas 2008 82.8
t4 Wisconsin 2008 82.8
t6 UCLA 2008 83.9
t6 Memphis 2008 83.9
t6 Louisville 2004 83.9
9 UCLA 2007 84.0
t10 Louisville 2008 84.1
t10 Michigan State 2012 84.1
t10 Wisconsin 2012 84.1

So five defenses in ten years have allowed less than 83 points per 100 possessions, and Ohio State is the only team to allow fewer than 82 per 100. But down at the end of that table there are two more defenses from this season, so perhaps this is just a defense heavy season? So here are the #1 defenses from each of the past 10 seasons, along with how much better they are than that year’s national average:

year team dEff avg % dif
2007 Kansas 82.2 101.8 23.8%
2012 Ohio State 81.4 100.8 23.8%
2008 Kansas/Wisconsin 82.8 101.9 23.1%
2009 Memphis 82.5 101.1 22.5%
2004 Louisville 83.9 100.8 20.1%
2006 Iowa 84.4 101.3 20.0%
2003 Kansas 84.2 101.0 20.0%
2010 Florida State 84.5 100.8 19.3%
2005 Duke 84.9 101.0 19.0%
2011 Florida State 86.2 101.3 17.5%

This puts Ohio State into a tie with the 2007 Kansas team. Not bad company. Regardless of how you look at it, this year’s Ohio State defense is playing historically well.

So how do they do it? It’s the power of hidden possessions. In basketball your team gets the ball and you either score or give the ball to the other team either through a missed shot or a turnover. Then it’s the other teams turn. Do this for 40 minutes and you have a college basketball game. But it seems that some teams get the ball more than others, and that’s where hidden possessions come in. And here’s the data:


Ohio State is circled in its rank of the top-20 defenses in terms of turning teams over. The Buckeyes cause teams to turn the ball over on 24.9% of their possessions, which is the 12th best nationally (out of 345 teams). Their typical game is about 68 possessions, which means they’ll force roughly 16 turnovers in any given game. A) that’s really solid, and B) it’s even more solid when you consider the other things they do well.

First, look at the column to the right of TO% (OR%) which shows how often OSU opponents rebound their own misses. In this case it’s 24.5% of the time, which is phenomenal rebounding on Ohio State’s part. Only two teams grab more defensive boards than the Buckeyes. Now scan up and down that chart. Only one other team is even in the top-100, and 16 of 20 are worse than 150th. Ohio State is 3rd! Simply put, for a number of reasons defenses which are good at forcing turnovers are not good at keeping opponents off the offensive glass. Except for Ohio State.

Go another column to the right (graphic is from kenpom.com, by the way) which is how often teams send their opponents to the foul line. Again, Ohio State is leaps ahead of any of the other top-20 turnover forcing defenses. Four others are in the top-100 in defensive FT Rate, and none better than 65th. 13 of 20 teams are worse than 150th. Again, teams that are good at forcing turnovers are not good at doing it without fouling. Except for Ohio State.

To map these hidden possessions we’ll assume a 68 possession game. Ohio State (12th nationally) will force you to turn the ball over 16 times, leaving 52 effective possessions for your team to do their scoring. In those 52 possessions, Ohio State opponents have averaged 30.8 misses shots per game. The Buckeyes allow 7.5 offensive rebounds. And since they foul so little, opponents will average 16.4 free throws.

Now, the same numbers with the average NCAA defense. In that same 68 possession game, the average defense will force 13.8 turnovers. So that’s 2.2 more scoring opportunities than OSU allows. Assuming the average team forced the same shooting percentage (they don’t) those extra 2.2 possessions would equate to an extra 1.3 missed shots, or 32.1 per game. Average teams allow opponents to grab 32.3% of their own misses, which in this case would be 10.4. The average team also has a 36.3% FT Rate which would mean 19.1 FTs.

So. Ohio State takes away an extra 2.2 of your possessions. They keep you from extending 2.9 possessions with offensive rebounds. And they don’t allow you 2.7 FTs that a normal team would. Those are the hidden possessions in a game, and this year’s Buckeyes is remarkable at finding them.

Now if they can just get that offense straightened out.