The PairWise Rankings Explained

Mar 5

What are the pairwise rankings, how do they work and why are they important?

WRITTEN BY JAMES BLENNAU

The PairWise Rankings are one of the great mysteries to casual hockey fans, and the statistical formulas behind them are a bit complicated. We at Ice Level are here to help you out and explain everything there is to know about the rankings system, how it operates, and why it’s important.

HISTORY OF THE PAIRWISE RANKINGS

In the early 1990s, the NCAA and its selection committee made a ranking system to objectively compare each of the DI teams with each other. The current criteria include the Ratings Percentage Index, Record vs. Common Opponents and Head-to-Head Record, with historical criteria including Record vs. Teams Under Consideration and Record in Last 16 (or 20) games. USCHO then used these criteria to create the PairWise rankings, a system used to mimic the selection committee’s system of ranking teams precisely, and has been extremely accurate ever since its creation.

HOW THE PAIRWISE RANKINGS WORK

I don’t exactly explain numbers as well as some of my friends at The Dan K Show, so here’s Lucas Jones with everything you need to know about how these rankings determine the best teams in NCAA hockey.

It’s a comparison system at heart. Each team is compared to every other team by a few key metrics:

RPI, or Rating Percentage Index - A quantity used to rank sports teams based upon a team’s wins and losses and its strength of schedule. The index is weighted for home and away results. Wins against opponents that hurt a team’s RPI are eliminated (Your index cannot be lowered as a result of a win, as it sometimes might for a win against a very low ranked opponent)
Record Against Common Opponents
Head-to-head Record

The team that “wins” in the comparison of each of these metrics is awarded points. 1 point to the team that wins the RPI category; 1 point per victory in the head-to-head metric; 1 point to the team that wins the record against common opponents category. The team with the most points in the comparison, is awarded 1 PWR point. No matter how many comparison points you earn, you can only ever win 1 PWR point per comparison. In addition, there are bonus points award for wins against Top 20 teams, and these are again weighted by home/away results. So when we see that Boston College has a PWR of 63, we know that they have earned those points by

Beating teams in the Top-20
Winning statistical comparisons against all of Men’s D1 hockey
Winning away games, which are weighted to have a higher value than home games

See? No nonsense. The numbers align with commonly held ideas about what makes teams good. Show up and win the big games, take care of business against lesser opponents, and keep your head on straight in opposing team’s barns.

HOW TEAMS ARE SELECTED FOR THE NCAA TOURNAMENT

In the NCAA DI Men’s Hockey Tournament, 16 teams make the final cut. Six teams earn automatic bids by winning the six conferences: Atlantic Hockey America, Big Ten, CCHA, ECAC Hockey, Hockey East and NCHC. The other 10 earn bids by being at a certain point in the pairwise rankings as at-large bids, similar to the NCAA basketball tournament. If any of the automatic bid teams are within the tournament field already, they allow lower at-large teams to enter the tournament.

Each team within the field is also split into a group of seeds ranging from one to four, with each team having an overall seed in the tournament from one to sixteen in case of head-to-head matchups in the Frozen Four. Higher-seeded teams will earn spots in regional sites closer to their campuses and fan bases. For example, if Boston College earns the number one overall seed, they will be the first team to land a regional site and likely end up in Manchester, New Hampshire, this year, sending number 2 overall Michigan State to Toledo, Ohio, number three overall Minnesota to Fargo, North Dakota and number four overall Maine to Allentown, Pennsylvania despite its proximity to Manchester. This continues throughout the two, three and four seeds until the tournament field is filled.

Regional sites are also always hosted by programs, and if a team hosts a regional, it is guaranteed to make that site, so if Penn State makes the tournament this year, they will play their first two games in Allentown. However, two teams from the same conference never meet in the first round unless necessary, and the committee spreads them across regions as much as possible.

That’s all there is to know about the PairWise…without getting too far into the statistics and selection. If you want to see the rankings in action, be sure to visit them at the source on USCHO.com or anywhere that links to it.

James Blennau