How important are NET Rankings to NCAA Tournament selection committee? Here's how it works

An explanation of the NCAA Evaluation Tool and its importance to the NCAA Tournament selection process

A quick "college basketball rankings" search on the internet will result in numerous media outlets and websites attempting to sort Division-I programs in some order based on current and past performances. Some rankings rely on human votes, while others use a combination of advanced metrics and their own secret formula. None of them are necessarily right or wrong in their assessments, but some are often more trusted than others.

Of all the highly regarded ranking systems, the NET (NCAA Evaluation Tool) is at the top of the food chain regarding how teams are seeded for the NCAA Tournament. Since the 2018-19 season, the NET Rankings have been used by the selection committee as the primary sorting tool for evaluating teams.

Here's what you need to know about the NET.

HOW THE RANKINGS WORK, QUAD GAMES EXPLAINED

The NET Rankings use a quadrant system to determine the quality of wins and losses based on game location and opponent's NET Ranking. "Quad 1" is the highest quality of games, while "Quad 4" is the lowest.

A team has a Quad 1 game if it plays a team ranked No. 1-30 in the NET at home, a team ranked No. 1-50 on a neutral site floor or a team ranked No. 1-75 on the road. Quad 2 games are home games against a team ranked No. 31-75, neutral site games against No. 51-100 and away games against No. 76-135. Quad 1/2 wins are considered the best indicators when looking at a team's NCAA Tournament resume

Quad 3 games are home games against teams ranked No. 76-160, neutral games against No. 101-200 and away games against No. 135-240. Quad 4 games are home games against a team ranked No. 161-353, neutral site games against No. 201-353 and away games against No. 241-353. Quad 3/4 losses can really hurt a team's postseason resume.

The quality of a team's wins and losses can change over the course of the season. For example, Gonzaga's loss at Washington was quantified as a Quad 1 loss at the time because the Huskies were ranked inside the top 75 in the NET. Since that game on Dec. 9, though, the Huskies have dropped to 77th in the NET after starting 3-5 in Pac-12 play, which now puts them in the Quad 2 category for Gonzaga's resume. 

The NCAA Tournament Selection Committee weighs Quad 1 wins heavily when looking at a program's postseason resume. Last season, Utah State (0-4 in Quad 1) was the only team to secure an at-large bid without a Quad 1 win, though it was 7-1 in Quad 2 and 13-0 in Quad 3 games. The Aggies didn't advance past the first round as a No. 10 seed.

The NET Rankings are updated daily until Selection Sunday on March 17. 

THE BIG FACTORS: TVI, NET EFFICIENCY AND STRENGTH OF SCHEDULE

The NET Rankings are mostly determined by four factors — Team Value Index, net efficiency, winning percentage and adjusted winning percentage — as well as many sub-factors within each of the four main determinants.

The Team Value Index, or TVI, is a result-based feature that accounts for teams beating quality opponents. especially away from home. The TVI takes into account the opponent, location and winner to determine a TVI score. How the NET deems which teams are "quality" opponents will be discussed later.

Net efficiency examines the difference between a team's offensive and defensive efficiency. Offensive efficiency is determined by a team's field goal attempts, offensive rebounds, turnovers and free-throw attempts. By dividing a team's total points by its total number of possessions, the resulting number is a team's offensive efficiency.

A team's defensive efficiency accounts for its opponent's field goal attempts, offensive rebounds, turnovers and free-throw attempts. Similar to offensive efficiency, a team's defensive efficiency rating can be found by dividing its opponent's total points by the total number of possessions.

After calculating both efficiency ratings, the NET subtracts defensive efficiency from offensive efficiency to find the difference, or the net efficiency.

Lastly, a team's strength of schedule plays a major factor in the NET. Strength of schedule accounts for a team's opponent and the site of each game, assigning each game a "difficulty score." These ratings aggregate across every game to create an overall expected win percentage versus a team's schedule. Road games generally are harder to win, followed by neutral site games and home games.

Strength of schedule is vitally important to Gonzaga when it comes to nonconference games. Mutli-team events like the Maui Invitational and neutral site games against really talented programs (UConn in Seattle, USC in Las Vegas) in theory help the Bulldogs' strength of schedule rating while giving them Quad 1 opportunities outside of WCC play, which doesn't feature as many chances to get quality wins.

WHAT ISN'T INCLUDED IN THE NET

Along with winning percentage, adjusted winning percentage and scoring margin, the NET doesn't account for when a game happens and in which order games occur. So Gonzaga's home opener against Yale counts the same as its road game at Pepperdine. That can differ from other computer analytics and rankings that do take into account previous results from months and even years past when ranking teams.

Previous versions of the NET utilized winning percentage, adjusted winning percentage and scoring margin. Those aspects were dropped from the formula in May 2020.