I’ve received a few e-mails about Creighton’s jump in the rankings after its win over Villanova. The following is representative of them.
How could Creighton jump from 13 to 2 with a win over Villanova? How could there be that much volatility in your program this deep in the season to create that type of move, especially at the top?
There’s been quite a bit of movement near the top of the ratings this season. This isn’t too surprising, because my updated algorithm minimizes the influence of mismatches, thus we’re left with less data to use, making the rankings more vulnerable to big moves. The appeal of including a 50-point win over bottom-feeders of one-bid conferences was that the ratings would be more stable this time of year.
But there’s something else going on, too, and that’s increased parity near the top of college basketball. Every year, someone will talk about how much parity there is college basketball and most analytically-minded people will roll their eyes. I can’t speak for others, but in my case it’s because there really isn’t much change in parity from season to season. It just seems like a boilerplate statement used to generate a feel-good story, and it’s never hard to find a coach willing to support that line of thinking. “Our league is so hard to win this season. There is just so much depth in our league,” said coach of every team favored to win its league.
This season, though, might actually be worth talking about in this regard. There a few things computers do better than humans in the college hoops world and measuring parity is one of them. And there is less of a difference between the second best team in college basketball and the 20th than we normally see.
Let’s look at the difference between the second-best and 20th-best teams in three different systems.
Sag Mas KP 2014 4.55 6.01 4.69 03-13 Avg 7.16 8.58 6.21
(For Sagarin, I’m using his predictor flavor and for Massey I’m user his power flavor. In both cases I’m taking the difference in points between #2 and #20. For my own system I’m taking the difference in efficiency margin multiplied by 67/100.)
This analysis ignores the top-ranked team because Arizona has a large cushion on the rest of the field right now. I’d guess that the number of times that #1 changes hands in the AP poll is largely what leads to pieces about parity. We haven’t had much of that so far and we’re getting deep enough into the season that if Arizona does lose they’ll still get some consideration to stay at #1, especially if Syracuse and Wichita State have lost by then.
At any rate, in a normal season the updated ratings algorithm will encourage more movement after a dominant win over a quality opponent, but the dynamics behind this season so far are increasing this effect as well. A lot of attention was given to North Carolina’s inconsistency and the UNC’s of the world are the reason for this. This season it’s not that any team can beat another team. That’s true every season. It’s that teams are getting bludgeoned by lesser foes then turning around and pulling upsets themselves.
UNC won at Michigan State by 15 and by nine over Louisville on a neutral floor, but at home has lost to Belmont and barely beat Davidson. Tennessee beat Virginia by 35, but lost by 8 to N.C. State at home, and N.C. State lost at home to UVa by 31! Sure, Villanova lost by 28 at home to Creighton, but they beat Providence in the same building by 30. Of course, Providence beat Creighton by 13, just before the Bluejays pummeled the Wildcats. Ohio State beat Nebraska by 31 in Columbus but lost the rematch in Lincoln. Indiana rushed the floor after beating Wisconsin, one of the Big Ten’s best teams, then proceeded to lose at home to Northwestern, possibly its worst. You can find these kinds of examples in any season, but I suspect it’s happening a little more frequently this season. Or maybe there’s something more complicated going on.
Regardless, there’s the potential for a big move when you have the sixth-most efficient road performance of the season and it comes against of the best defenses in the country. It might be a stretch to say Creighton is a top five team, but that’s closer to the truth than not having them in your top 25. The real point of all of this is that there isn’t much difference at all between the fifth-best team and the 15th-best in a normal season, and it looks like there’s even less of a difference this season.