Parity? (02/26/14)

By John Ewing
How much of a difference is there between the top seeds in this year’s NCAA tournament? How many teams have a legitimate chance of winning it all?

The top five of our preseason top 25 included Michigan State, a team returning five of its top six scorers from a Sweet Sixteen squad the season before; Kansas, which recruited Andrew Wiggins, Joel Emblid, Wayne Selden and others; Syracuse, a Final Four team that was returning its top scorer; Kentucky, the unanimously selected best recruiting class in the country; and Michigan, last year’s national runner-up.
As the season progressed, we anticipated one of these teams to separate itself from the rest. Instead, the opposite has happened. None of these teams remains in the top five of our current Power Rankings (Kansas is the closest at No. 6). This is the first year of our College Basketball Power Rankings when a preseason top five team has not held one of the top five spots this late in the season. What is the cause of this? Parity.
Parity, balance, whatever you want to call it, is evident more than ever at the top of college basketball. One way to measure the parity in the sport is to use our Power Rankings, which are created by "playing" every team against every other team 50,000 times and then ranking by overall winning percentage in those games. Below are the expected win percentages for each team in our Top 25 from the final Power Rankings before the 2013 NCAA Tournament compared to our most recent rankings from this season. By examining the expected win percentages, we can get a feel for how much balance there is this season relative to to last year.
Looking at the expected win percentages for 2013 and 2014, it's obvious that the 2013 numbers are stronger for the teams at the top of the rankings. Louisville, for example, was ranked number one and expected to win greater than 98% of its games against all 345 Division I programs (Indiana to Abilene Christian and everything in between) as of Selection Sunday last season. Florida, the current No. 1 team in our rankings, is only expected to win 93% of those games. The expected win percentages for the top 25 in 2014 are weaker as a whole compared to 2013, meaning the gap between the teams at the top is closer than ever. 
In 2013, there were five teams in the top 25 within five percent of No. 1 Louisville's expected win percentage. In 2014, ten teams are within five percent of No. 1 Florida’s expected win percentage. In 2013, teams in the Top 15 were within a 10% difference of Louisville. In 2014, nearly the entire top 25 is within 10% of the No. 1 Florida.
What does this tighter gap mean? In terms of seeding for the NCAA tournament, there is not likely to be much difference between a No. 1 seed and No. 4 seed.
In 2013, Louisville, Indiana and Florida had distanced themselves from the rest of the field. These schools combined to win 47.3% of all simulated tournaments as of Selection Sunday. In our most recent bracket analysis, it would take the combined odds of Duke, Florida, Kansas, Creighton, Arizona, and Louisville to match that level of tournament dominance.
With Selection Sunday just a few weeks away, there is no clear favorite to win the 2014 NCAA Tournament. Last year there were 11 teams with a 2% or greater chance of winning it all as of Selection Sunday; this year there are 17 teams with a legitimate chance (2% or greater) to win the title. 

It is called March Madness for a reason and this season may be the maddest of them all. 
2013 and 2014 - Power Rankings and Expected Win Probabilities

Rank Team (3/17/2013) 2013 Win Pct. Team (2/23/2014) 2014 Win Pct.
1 Louisville Cardinals 98.28 Florida Gators 93.27
2 Indiana Hoosiers 97.82 Duke Blue Devils 91.48
3 Florida Gators 97.27 Creighton Bluejays 90.99
4 Duke Blue Devils 94.16 Louisville Cardinals 90.94
5 Gonzaga Bulldogs 94.06 Arizona Wildcats 90.11
6 Ohio State Buckeyes 92.73 Kansas Jayhawks 89.73
7 Kansas Jayhawks 92.49 Virginia Cavaliers 89.66
8 Michigan State Spartans 91.92 Iowa Hawkeyes 88.97
9 Michigan Wolverines 91.84 Villanova Wildcats 88.85
10 Miami (FL) Hurricanes 91.73 Syracuse Orange 88.66
11 Syracuse Orange 90.71 Wisconsin Badgers 87.55
12 Wisconsin Badgers 89.90 Michigan Wolverines 87.45
13 Georgetown Hoyas 89.52 Ohio State Buckeyes 87.10
14 Pittsburgh Panthers 88.97 Wichita State Shockers 86.67
15 North Carolina Tar Heels 86.83 UCLA Bruins 86.62
16 Missouri Tigers 86.58 Michigan State Spartans 86.01
17 New Mexico Lobos 86.45 Kentucky Wildcats 85.96
18 Creighton Bluejays 86.33 Pittsburgh Panthers 85.03
19 Arizona Wildcats 86.29 North Carolina Tar Heels 84.30
20 Kansas State Wildcats 86.05 Cincinnati Bearcats 84.09
21 Saint Louis Billikens 85.92 SMU Mustangs 83.10
22 Marquette Golden Eagles 85.80 Connecticut Huskies 82.59
23 Oklahoma State Cowboys 85.45 Saint Louis Billikens 82.53
24 Colorado State Rams 85.19 Iowa State Cyclones 82.38
25 VCU Rams 84.98 Tennessee Volunteers 82.10