What is going with Xavier in the NET?

Jan 27, 2023 - 5:31 PM

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Xavier is quite good this season. They are 9-1 in the Big East, 6-3 in Quad One games, have lost once since their Thanksgiving tournament, and have beaten Marquette, UConn (twice), and Creighton. With all of that known, a question springs to mind:

First off, here is what the NCAA says about the NET

The remaining factors include the Team Value Index (TVI), which is a result-based feature that rewards teams for beating quality opponents, particularly away from home, as well as an adjusted net efficiency rating. The adjusted efficiency is a team’s net efficiency, adjusted for strength of opponent and location (home/away/neutral) across all games played. For example, a given efficiency value (net points per 100 possessions) against stronger opposition rates higher than the same efficiency against lesser opponents and having a certain efficiency on the road rates higher than the same efficiency at home... The NET includes more components than just winning percentage. It takes into account game results, strength of schedule, game location, scoring margin, net offensive and defensive efficiency, and the quality of wins and losses.

That’s not exactly opaque. What it leads to is a better system than the RPI, but also one that can lead to questions like the one our man Jesse had above. There is some sense in what Jesse says. After all, Xavier has beaten some very good teams on the court, not paper. They’ve beaten UConn twice now. What kind of system would take those results and turn out this table?

One thing to remember is that while the human impulse is to highly rate head to head and recent matchups, the NET and KenPom both try to weight the entire season. Both systems treat every game the same from 1-30 and try to avoid recency bias when it comes to overall ranking. It’s also worth remembering that these are predictive metrics, not solely a results based metric that would ignore efficiency and the four factors. That can impact how teams stack up and can explain why the AP poll or ELO seem more intuitive or how a purely results metric like SOR spits out wildly different results.

For starters, Xavier’s loss to DePaul really weighs down the resume. A lot. That’s a really bad Q3 loss to a really bad team. UConn also has a Q3 loss, but theirs came to #85 St. John’s. The worst loss Marquette has is Wisconsin. Creighton... I have no idea. Creighton is 1-5 in Q1 and has a loss to Nebraska. That’s not as bad as DePaul, it’s not really close, but it’s still a Q3. The Bluejays are riding excellent efficiencies that the predictives really like.

Secondly, UConn especially has pummeled lesser competition. Margin of victory isn’t involved in the metrics, but the efficiency numbers that come with bludgeoning Long Island by 51 don’t just go away. Xavier only has three 20 point wins all season, UConn has eight, including two against Q2 opponents. Playing that efficiently will make the metrics, the polls, and everything else love you, even if you drop a couple of close ones against a top 15 team. Marquette beat Baylor by 26. Do something like that in a Q1 game and metrics will love you now and forever.

Essentially what these measurements want to see is efficiency. The four factors have a big impact. Xavier is winning games, but just like on the court, their defense is hurting them. No computer, especially one trying to create a predictive metric, is going to look at a team with the 93rd best defense (and trending down) and a loss to #153 and see greatness. Xavier’s offense bouys them a bit, and that’s how they land in the top 25. Remember, these things are not just measuring a binary result.

There is a metric that does that, though. It doesn’t factor in the Selection Committee’s process at all, but it’s out there. That metric is called Strength of Record (SOR). Per ESPN, “Strength of Record (SOR) is a measure of team accomplishment based on how difficult a team’s W-L record is to achieve.” SOR is, theoretically, a measure of what a team has done, regardless of how they have done it. Below is what the Big East looks like when sorted by SOR. I left BPI, a predictive metric, in to provide some contrast.

So, Jesse (and everyone else), the answer isn’t a simple as you might like. Xavier is damaged in everything by that loss to DePaul and that defense. Metrics that like efficiency don’t like the Musketeers as much as they like the other Big East powers. Metrics that are weighted more on win/loss tilt toward Xavier. For now, X is a really good team with a couple troubling black marks. No matter how you slice it, though, they are sitting pretty resume wise right now.