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Al Featherston: K's New Stat

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Mike Krzyzewski took a look at the box score after Duke's recent victory over Elon and one stat jumped out at him.

He pointed out that Elon had managed just 10 assists. One night earlier, the Devils had allowed Cornell just eight assists.

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To Coach K, those numbers were significant.
"I think our defense has been good the whole year," he told the media. "We don't give up any easy shots. That is why we are not assisted a lot. I don't follow all of our stats over the years; it's been too many years, but I would have to think this is one of the least assisted upon teams.

"It's a new stat."

"We will figure that out…A lot of the games there are single-digits assists, and today there are 10 and then there are more turnovers than assists. I like that about our team."

Well, let's start with the numbers. Rather than raw assists, which are dependent on game tempo, let's look at the assist rate - how many opponent field goals are the result of assists. Through 12 games (including Saturday's victory over Santa Clara), Duke's opponents have combined for 105 assists on 280 field goals.

That's 37.5 percent

It turns out that Krzyzewski is right - the 2012-13 Blue Devils are allowing the lowest percentage of assisted field goals in his 32-year tenure. Or, as Coach K put it, this is his "least assisted upon" Duke team.

The five lowest before this season:

  • 2005 - 41.9 percent
  • 2009 - 42.9 percent
  • 2012 - 44.0 percent
  • 2006 - 46.1 percent
  • 2008 - 47.6 percent

In contrast, the five worst seasons:

  • 1982 - 60.0 percent
  • 1987 - 55.0 percent
  • 1998 - 54.0 percent
  • 1988 - 53.3 percent
  • 1990 - 53.2 percent

I list the best and worst because I think Krzyzewski's observation raises an interesting question. While he's unquestionably right that this is his "least assisted upon" team, how significant is his new stat in predicting defensive performance?

I'm not as sure of that.

For instance, the 2005 team - which was the least assisted upon before this season - was ranked the No. 1 defense in the nation that season by Ken Pomeroy. And the 1982 team that gave up a Duke-high 60 percent of assisted field goals, was the worst team in the Krzyzewski regime.

That seems to be a pretty clear link.

On the other hand, the 2010 national champs and the 2004 Final Four team both allowed a very average (for Duke) 48.9 percent of field goals to be assisted. Yet, Pomeroy voted both defenses No. 4 nationally.

And while Pomeroy's rankings don't go back to 1988, most Duke fans would tout that Billy King-Robert Brickey team as the best defensive team in the K era … yet, the '88 Blue Devils allowed 479 assists on 899 field goals - a terrible (by Duke standards) 53.3 percent.

So can we really count K's new stat as a significant defensive metric?


Coach K mentioned a different metric - the ratio of opponent assists to turnovers forced. After the Santa Clara win, he suggested that was a very significant statistic to him.

The ACC (and NCAA) measure assist to turnover ratio. But they're talking about the ratio of a team's own assists vs. its own turnovers. And there is an official stat measuring the number of turnovers a team commits vs. the number of turnovers it forces.

As far as I know, nobody measures the ratio of assists allowed vs. the number of turnovers caused. So maybe we should credit Krzyzewski with another new stat.

Okay, let's check that one out.

Through 12 games this season, Duke has allowed 105 assists and forced 183 turnovers.

That's a ratio of 1.74 turnovers for every one assists.

As it turns out, that's also the best ratio in Krzyzewski's 32 seasons. The previous best five:

  • 1998 - 1.58
  • 2005 - 1.56
  • 2009 - 1.56
  • 1989 - 1.56
  • 2008 - 1.49
  • 2003 - 1.48
  • 1997 - 1.47
  • 1991 - 1.47

The worst rate - and the only time under Krzyzewski when Duke allowed more assists than forced turnovers - was 1982 (0.76). More evidence that was Krzyzewski's worst defensive team (and it wasn't so great on offense either).

Once again, the 2005 team - rated No. 1 in the nation defensively by Pomeroy - posts very good numbers in this new stat. The other top teams were all very successful.

Obviously, there are other defensive metrics that matter.

I have a friend who is a Wake Forest fan and he argued that the Deacons of the early and mid-1990s (the Tim Duncan years) were the best defensive teams around - because of their opponents' field goal percentage was so low.

There's something to that argument. It is possible to play good defense by packing the defense around the basket, denying good shots and hitting the defensive boards. The only negative to that strategy is that such teams don't force many turnovers. Hence, they get little offense from their defense. It's also hard to speed an opponent up out of that formation when you trail late.

Krzyzewski usually - not always, but usually - believes in extending his defense. His teams play the passing lanes. The good ones turn opponents over, creating easy chances on offense. The negative to that strategy is that is does sometimes allow easier shots and, hence, a higher opponents' field goal percentage.

There's also a very subtle reason that Duke's defensive rebounding numbers are sometimes shaky. Most teams - even most man-to-man teams -- defend by trying to keep a defender between the man and the basket. Duke usually plays between the man and the ball, which sometimes allows opponents an easier path to the boards. And when the defense is extended, there are less defensive players closer to the basket.

Some of Duke's best teams have been suspect on the boards. There are exceptions - the 2010 national champs were a dominant rebounding team … partially because of personnel and partially because that was one of the rare seasons when Krzyzewski dialed down the pressure and played a more defend-the-basket scheme than normal.

That's why the 2010 team allowed opponents to shoot as mere 40.1 percent from the field - the third lowest in the Krzyzewski era. Only 2005 (39.0) and 1999 (39.1) were lower. On the other hand, even some of Coach K's greatest teams gave up high field goal percentages. The 1992 national champs allowed opponents to convert 46.7 percent of their chances - that's the highest average since his early years (that terrible 1982 team allowed 51.8 percent).

As longer as we're looking at defensive stats, here's an eye-opener:

Through 12 games this season, Duke's opponents are shooting just 38.8 percent from the floor. That's better than the 39.0 in 2005; the 39.1 in 1999 and the 40.1 in 2010.

That happens to be the lowest percentage allowed by a Krzyzewski-coached team. So Duke is doing a good job defending the basket while still forcing turnovers and denying assists.

When you put it all together - the least assisted against Duke team; the most turnovers forced per assists allowed; the lowest opponents field goal percentage - can you make the argument that this is Krzyzewski's best defensive team?

Well, you can certainly make that argument, although there are also those - think Ken Pomeroy - who would disagree. Pomeroy currently ranked Duke's defense as the nation's 9th most efficient in the nation - good, but not nearly K's best (it's tied for the 6th best Duke defense in the last 11 years).

There's also one more huge caveat - these are partial results, though 12 games. Normally, Duke (and most other big-time teams) fatten up their stats on pre-conference opponents.

But this year may be different. Duke has actually completed the toughest part of its schedule. Games against the likes of Louisville, Ohio State, Kentucky, Minnesota, Virginia Commonwealth and even Temple are as tough or tougher than anything the Blue Devils will face in the ACC. Even Florida Gulf Coast and Elon are not terrible teams - they are currently rated higher than Wake Forest or Boston College at the bottom of the ACC. Only Georgia State and Cornell are true patsies.

The point is that there is no reason to think Duke's defensive stats may be inflated by the non-conference lineup. The Devils still have to sustain their success, but it's not like they are going to be playing tougher teams.

This is turning into one of Coach K's better defensive teams. Quinn Cook has upgraded the on-the-ball pressure and freshman Rasheed Sulaiman has provided a strong defender on the wing. Tyler Thornton has been a defensive demon off the bench and senior Ryan Kelly has been an unsung stopper in the post. Backing everything up - Mason Plumlee has been one of the best shot-blockers in the ACC.

"I think we have played really hard on the defensive end," Krzyzewski said after the Elon game. "You have to give credit to them. They are playing hard. They are playing good defense."

Maybe even historically good defense.

"We are a VERY good defensive team," Coach K added after the Santa Clara win.