Wednesday, May 21, 2008

Offensive and Defensive Ratings -- An Arial View

I wondered how the sixteen Big East teams compared with each other with respect to efficiencies -- offense and defense -- so I pulled down the schedule data from Ken Pomeroy's Basketball Prospectus Web Site to see if there was anything interesting to plot. I looked at just the conference games. The conference-wide offensive and defensive effiencies averaged out to 102.7 -- which I frankly thought might be high. That both offense and defense averaged to the same number however was "proof" that it was correct. Taking the "average" as 0,0 I subtracted the average from each team's offensive efficiency and then subtracted each team's defensive efficiency from the conference-wide average. That gave me points, relative to the conference-wide average, to plot for each team. Using this technique I was able to plot those teams with "above average" defenses above the X-Axis, and those with "above average" offenses to the right of the Y-Axis. Those teams with "above average" offensive and defensive efficiencies were grouped into the upper right hand quandrant.

The chart (above) confirms "knowns" rather than reveal "unknowns". Five of the teams grouped in the upper right quandrant, Georgetown, Louisville, Connecticut, Marquette and West Virginia, finished the regular season with five of the six best records in the conference. The chart confirms that Georgetown and Louisville, by consensus the two strongest teams in the conference, were, as confirmed by the scatter chart, clearly separated from the rest of the conference. Good things had been predicted for Syracuse (the sixth team in that quadrant), though the Orange finished the regular season riding the bubble, and after losing their first round game in the Big East Tournament to Villanova, finished the season with an NIT run. Having Notre Dame positioned below the 0,0 point on the Y-Axis might seem to undermine the chart's credibility, but consider that the "below average" efficiency identified here is defense. Notre Dame in the Mike Brey era is noted for both it's potent offense (best in the conference in 2006-07, but nearly as notorious for it's lack of defense. This season shows yet again that Notre Dame's offense is strong enough to mask the team's suspect defense. While strong offense (coupled with "just enough" defense) may be good enough to get by in the Big East, it may also explain the series of early NCAA exits the Irish have taken in the past 2 post seasons.

The mirror opposite quandrant (lower left) also seems to confirm what a consensus suspected. Three of the four teams in this quadrant finished among the bottom five. Rutgers and South Florida did not make the conference tournament. Providence barely had time to unpack before being sent home with a first round loss.

The data used for each team is below. For each team I have included a link to that team's "Game Plan" page over at Ken Pomeroy's web site. Notice that Villanova's ratings, offensive and defensive were nearly identical.

TeamORtgDRtgX AxisY Axis
Cincinnati (8-10)98.1103.1-4.6-0.4
Connecticut (13-5)110.8102.08.10.7
DePaul (6-12)104.6111.31.9-8.6
Georgetown (15-3)104.593.11.89.6
Louisville (14-4)105.991.43.211.3
Marquette (11-7)
Notre Dame (14-4)110.1103.67.4-0.9
Pittsburgh (10-8)109.2104.76.5-1.9
Providence (6-12)102.7108.6-0.1-5.9
Rutgers (3-15)88.4105.4-14.3-2.7
Seton Hall (7-11)103.3109.00.6-6.3
St. John's (5-13)90.1102.2-12.60.5
South Florida (3-15)98.4108.6-4.3-5.9
Syracuse (9-9)103.7102.00.90.7
Villanova (9-9)100.3100.2-2.42.5
West Virginia (11-7)107.499.64.73.1
Standard Deviations6.455.46

A few observations...

  1. While Villanova's defense was the focus of a good deal of criticism within the Nova Nation, the table demonstrates it was the team's stronger feature during the Big East season. A few defensive efforts like the games at Georgetown and St. John's and the homestands against Connecticut and Pittsburgh come to mind. The Wildcat's "nearly even" ratings (100.3 vs 100.2) provide a hint of the team's 0.500 record in conference play. The defense, while better than average for the conference was not on par with the performance of recent teams.
  2. For the Big East this season, offense seemed to matter most. Note that St. John's, while playing slightly above average on defense, was significantly off on offfense. And their record (5-13) reflected that very big step back from last season.
  3. Cincinnati, Syracuse and Villanova were the three teams whose points fell closest to the intersection of the X and Y Axis. Those three also finished with records within +/- 1 of 0.500.


Pete said...

I might be imagining things, but aren't the axes mislabled on that chart? Offense is the x-axis but it says defense, and vice-versa...?

greyCat said...

When I set up the table I had "intended" for offense to be the X-Axis Pete, but when Excel graphed the points it appeared to me that it plotted the defense relative to the X-Axis and the offense relative to the Y-Axis. The conference average (point 0,0 on the graph) was 102.7 and relative to that average Villanova's points were -2.4 (offense) and 2.5 (defense).