Using defensive efficiency to identify contenders and pretenders

There are a few charts I compile every year about this time, when conference play is beginning in earnest, that help make sense of a muddled college basketball world. This is no glamorous procedure -- just raw numbers -- but it tends to be a more valuable learning experience than trying to read into coaches' quotes about teams maturing or gelling or being gutsy, because there's no way to spin your efficiency numbers. (For the uninitiated, efficiency is how many points you score and allow per 100 possessions, according to kenpom.com).

The first chart hammers home the central point: No Final Four team in the past five years has been ranked outside the top 25 in adjusted defensive efficiency (a competition-adjusted figure). And only two Elite Eight teams in the past five years have ranked outside the top 50 in adjusted defensive efficiency. It's unlikely that a team will make a deep NCAA tournament run with just a good offense, and only a mediocre D. See for yourself:

Kansas, as the chart above shows, was not your national champ by accident. The Jayhawks had, by far, the biggest efficiency margin in the country. And even the Cinderella, Davidson, had a solid profile, with the 31st-ranked defense to complement Stephen Curry's scoring power.

The Contenders

Now that we've established a profile of sorts for title contenders, we can use it to analyze the teams in the Associated Press Top 25 (plus the top five in the "others receiving votes" section). There are seven teams in that bunch that, thus far, fit the statistical mold of a contender, with both their adjusted offensive and defensive efficiency ratings in or near the top 20:

• The argument for Pittsburgh as North Carolina's prime title challenger is a strong one. The Panthers are the only team in the country in the top 10 in both adjusted offensive and defensive efficiency.

• North Carolina is in a situation similar to last season, when its offense was a juggernaut but its defense was just short of elite. Fortunately for the '08-09 Heels, there aren't many teams out there that can expose their defensive shortcomings (as Kansas did in San Antonio).

• The clear surprise on this list is West Virginia, which came into Tuesday's game against UConn with the nation's No. 2-ranked defense and a decent offense to match.

• Despite its freefall out of the top 25, Gonzaga shouldn't be entirely written off. The Zags' entire body of work suggests they're still capable of contending.

The Sleepers

Which teams outside the AP's top 30 have efficiency profiles that warrant attention? These seven unranked teams with decent résumés -- adjusted efficiency rankings in the top 50 on both sides of the ball -- are the best sleeper candidates:

• Illinois might be the team to watch here. It already has a top-20 defense and has only recently begun to work prolific scorer Alex Legion into the offensive mix. Legion became eligible in December after transferring from Kentucky midway through last season, and if he develops into a real outside threat, the Illini's offense could be efficient enough to make them a truly dangerous team.

• Missouri isn't receiving much national attention, but the Tigers emerged from the nonconference season with two quality wins (over USC and Cal) and are actually playing more efficiently than any other team in the Big 12. Keep Mizzou on your radar.

• My prime sleeper pick last year, from this chart, was West Virginia. And that turned out rather well.

The Dreaded Early Warnings List

Which teams in the AP's top 30 might be suspect in the postseason because of their lack of a quality defense? Eight ranked schools had adjusted defensive efficiency ratings outside the top 60. Unless they shape up over the next few months, the odds are stacked against them making deep NCAA tournament runs:

• The biggest red flag on this list is Notre Dame, which could climb back into the top 10 of next week's polls after beating Georgetown on Monday night. The Irish are actually much worse defensively this year than they were last year, when they lost in the second round of the NCAAs to Washington State. As of Tuesday Notre Dame ranked 146th in adjusted defensive efficiency, which means that they're the worse defensive team in the top 25 ... and it's not even close.

• Oklahoma is by no means a lost cause, but as of now, the statistics say it shouldn't be taken seriously as a Final Four contender. The Sooners are certainly capable of defending -- last season, when they weren't as good overall, their defense was ranked 31st -- but they've been too lax on that end of the floor in '08-09. They let every decent opponent this season (Davidson, USC, VCU and Arkansas) score more than one point per possession.

• Arkansas is likely to find itself in the polls after beating Oklahoma and Texas in a seven-day span, but the overall efficiency stats suggest that the Razorbacks aren't an elite team. It's possible that they just played down to the level of their lesser competition early in the season ... but I still don't expect them to finish with a better SEC record than Tennessee or Kentucky.