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Andy Wittry | NCAA.com | January 6, 2020

How the 'championship arc' may reveal this season's top Final Four contenders

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The NET rankings have made their 2019-20 debut, as did the NCAA team sheets, and we're less than 100 days away from Selection Sunday, so it's not too early to look at what teams fit the statistical profile of past national champions.

I'm going to do it with something I like to call the "championship arc." Here's how it works.

You'll often hear that a team needs to be ranked in the top 20 or top 25 of both offense and defense in order to win a national championship.

The spirit of that statement is generally true but it's not necessarily accurate enough — for several reasons.

When you graph the pre-NCAA Tournament adjusted offensive and defensive efficiency ratings of recent Final Four teams, you'll notice a pattern.

Most national champions are either historically elite on at least one end of the floor or they're very good on both offense and defense. You can win a title by simply being pretty good on both ends (Syracuse in 2003, UConn in 2011) but remember both of those teams were led by historically great college players — Carmelo Anthony and Kemba Walker — who engineered two of the most memorable NCAA tournament runs of all time.

By connecting the dots, literally, between Villanova's pre-NCAA tournament offensive and defensive efficiency in 2018, when the Wildcats had the best offensive efficiency rating of any national championship team during the kenpom.com era (which dates back to 2002) but the worst defensive efficiency rating, and the pre-NCAA Tournament efficiency ratings of Louisville in 2013 (the Cardinals' national championship was later vacated), you'll notice an arc inside which the majority of the last 18 national championships fall.

This is the championship arc, which is shown below to reflect the adjusted efficiency ratings of the top 15 teams (in red) on kenpom.com through Dec. 15.

Tap or click on the graphic above to expand.

In addition to the past champions that are positioned inside or on the arc, two other champions are located just outside the arc, leaving just three of the last 18 national champions that are statistical outliers compared to their national champion peers — Syracuse in 2003 and UConn in 2011 and 2014.

Just 14 of the other 54 Final Four teams from 2002 through 2019 fall inside or touching the championship arc, while the other 40 fall outside of it. This shows that even if a team makes a Cinderella run to the Final Four a la VCU in 2011 or South Carolina in 2017, the best teams are typically the ones that ultimately cut down the nets.

So while it's not a hard-and-fast-rule that a school's pre-NCAA tournament efficiency ratings must fall inside the arc to win a national championship, you'll find that most recent national champions fit this similar profile, which we can then use to project forward for this season.

So who's the best team this season?

As you'll notice in the scatter plot above, there's not a single team this season that falls inside the championship arc.

There's a pretty simple explanation for that: the new 3-point line.

This season the 3-point line was moved back to 22 feet, 1¾ inches, which changes where current teams fall on this scatter plot relative to their historical peers because offensive efficiency across the sport has decreased while defensive efficiency has improved.

A few teams, most notably Ohio State, are not far outside the championship arc. The Buckeyes, along with teams such as Michigan State, Gonzaga, Kansas, Louisville and Duke are a similar distance outside the arc as Florida in 2006 and UConn in 2004 and 2011, for reference.

In an attempt to adjust the championship arc to the extended 3-point line, we found that from the 2002 season to the 2019 season, the average adjusted efficiency rating in college basketball was 103.5, compared to this season's national average of 99.8, which is a difference of 3.7 points per 100 possessions.

Therefore, I adjusted the lower bound of the championship arc by 3.7 points per 100 possessions in an attempt to reflect how the current 3-point line has caused a dip in offensive efficiency and improved defensive efficiency nationally.

Ohio State is easily inside this new arc, which we'll call the 3-point-adjusted championship arc. Michigan State, Louisville and Duke fall just outside of it. Kansas is just outside of it, too.

Tap or click on the graphic to expand.

What this means for the rest of the season — and March Madness

This college basketball season could be on pace for a historic level of parity, particularly at the No. 1 spot in the AP Top 25 poll.

Preseason No. 1 Michigan State lost its season opener on Nov. 5 to Kentucky, which then took over the No. 1 spot in the AP poll before a home loss to Evansville on Nov. 12. Two weeks later, No. 1 Duke fell at home in overtime to Stephen F. Austin, which allowed fellow ACC member Louisville to assume the No. 1 spot, only to lose to unranked Texas Tech on Dec. 10. Kansas took over the No. 1 spot on Monday.

The record for the most teams ranked No. 1 in a season was seven in 1983. Ohio State, Maryland and Gonzaga fit the profile of teams that are in the top 10 in the AP poll with zero or one loss that could potentially climb to No. 1 at some point this season.

All that goes to say that a potentially historic level of parity in the 2019-20 regular season would presumably lead to a wild four weeks during the NCAA tournament. There are upsets every season during March Madness but there could be even more than usual if the revolving door at No. 1 (and beyond) in the AP poll continues.

Despite the instability at the top spot in the polls, the championship arc tells us that through mid-December, two of the teams that best meet the requirements of recent national champions are Ohio State in Year 3 of the Chris Holtmann era and Louisville in Year 2 under Chris Mack, along with familiar faces at Gonzaga, Michigan State, Kansas and Duke.

Also interesting is that while reigning national champion Virginia is elite on defense, the Cavaliers' offense is lagging behind, even in comparison to adjusted standards based upon the extended 3-point line. Their offense needs to make significant improvements if Virginia is going to fit the profile of past Final Four teams, let alone past national champions.

However, last season's national runner-up, Texas Tech, proved that being elite on one end of the floor, plus having enough time until Selection Sunday to improve on the other end, is reason enough for fans to have hope that their team can make the Final Four.

The Red Raiders' offense ranked No. 140 national in adjusted offensive efficiency on Jan. 28, according to kenpom.com, and after their run to the national championship game, they finished the season ranked No. 25 on offense.

So when you hear that your team needs to be ranked in the top whatever to win the national championship, that might be true, but there's a lot more to the story. The championship arc is here to add context and fill in the details.

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