Sports

WHITROCK: Defense first? Think again

Most baseball fans with anything beyond a casual interest in the sport have heard of Bill James, one of the fathers of sabermetrics and an advocate of carefully reasoned statistical analysis. James and others have helped to advance the sport of baseball by examining age-old questions about the game ‘-‘- specifically, questions related to the value of individual players ‘-‘- from new angles.

Basketball, being somewhat more fluid and team-oriented than baseball, presents different challenges for statisticians. In particular, tempo has a significant effect on basketball players’ and teams’ raw totals. Imagine if teams in the American League played 11 innings instead of 9. It wouldn’t make sense to equate players from different leagues based on raw totals, or even per-game averages, because the idea of what constitutes a game would be a variable.

Comparing baseball players in different inning environments (and therefore different scoring environments) doesn’t make sense, but the basketball analog of that comparison is made every day. Teams playing fast-paced basketball are regularly hailed as offensive powerhouses. Sometimes those pronouncements are valid ‘-‘- Tyler Hansbrough and the Tar Heels say hello ‘-‘- but for other teams, like the NBA’s Golden State Warriors and New York Knicks, the high point totals are a product of the pace, not offensive efficiency.

How is the problem corrected? If you’re a stathead, you already know the answer: take tempo out of the equation by measuring output on a per-possession basis. Pace can skew numbers one direction or the other, but tempo-free stats remain unaffected.

Consider the Terriers’ men’s basketball season thus far. BU is half a game ahead of Vermont for first place with a 7-2 record. Heading into last night, Vermont is averaging almost three more points per game than BU on offense and has a 1.3 points-per-game advantage on defense. BU has played six overtimes in conference play to the Catamounts’ one; without those overtimes, the gap in offensive output would be significantly larger.

If it appears that Vermont’s major advantage over BU is an offensive one, think again! Going into last night’s showdown with Binghamton, Vermont averages 67.5 possessions per 40 minutes in conference play. In contrast, 40 minutes of typical Terrier basketball include less than 61 possessions.

Adjusting for tempo reveals the truth: BU and Vermont have offenses of equal efficiency, averaging 113.3 points per 100 possessions. The Catamounts’ defense gives Vermont its edge, with an advantage of nearly six points per 100 possessions.

Wait a second. Isn’t BU head coach Dennis Wolff known for his team’s proficiency at the defensive end? That would be correct. Wolff is also known for preferring a man-to-man defense, which does nothing to explain the Terriers’ heavy use of zone defenses this season. Reputations, even those based on years of consistent behavior, don’t necessarily reflect the current situation.

BU’s primary strength being on the offensive end isn’t the most obvious of statements. However, it’s supported by the facts. Not that the Terrier defense is particularly deficient ‘-‘- the America East teams not named Vermont all allow more points per possession than BU ‘-‘- but there’s more room for improvement when the Terriers don’t have the ball.

More precisely, BU has problems getting the ball back. Field-goal percentage isn’t an issue ‘-‘- BU’s defense is the best in America East at defending both 2s (43.9 percent in conference play) and 3s (27.1 percent) ‘-‘- but rebounding and turnover margins are.

The Terriers allow conference opponents to grab nearly 38 percent of their own misses; only Hartford is worse on the defensive glass. BU’s America East opponents turn the ball over on just 17 percent of possessions, the third-lowest rate in the conference.

Given the Terriers’ ability to defend opposing shooters, it isn’t necessary to be outstanding on the defensive glass or at forcing turnovers. Unfortunately, BU’s performance in those categories is well below the league average. In this instance, regression to the mean would be a good thing, so long as opponents continue to miss from the field.

To be fair, Wolff has been dealt an unfamiliar hand this year. The decision to implement frequent use of zone defenses reflects that. It’s certainly conceivable that BU’s struggles with defensive rebounding and opponent turnover rates are a by-product of a defensive scheme designed to frustrate shooters. Still, if the Terriers hope to improve, rebounding and forcing turnovers should be the focus.

It doesn’t take much improvement, either. The conference’s mean defensive rebounding percentage is 66.5 percent; the mean turnover rate is 20.4 percent. Improvement to those levels would result in BU’s defensive efficiency being equal, if not superior, to that of the Catamounts.

There are positive signs to be found. BU has exceeded its average defensive rebounding percentage for each of the past four games, and opponent turnover rates have favored the Terriers in their two most recent contests. The challenge is finding ways to continue to improve without getting away from the defense’s strength: contesting shots.

Albany is in town tonight. A month ago, BU stopped Albany’s shooters, but couldn’t keep the Great Danes off the boards. If BU’s defense can step up and correct its deficiencies, the offense should carry the day.

Yeah, the Terriers are an offensive powerhouse. When’s the last time you heard that?

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