In theory, gambling based on point spreads (as opposed to straight-outcome betting) should not only reduce the magnitude of harm of gambling-related "fixes" but also make certain kinds of cheating easier to detect if someone actually crunches the numbers.
Consider a corrupt referee who needs the home team to win by at least five points and who does something to cause the home team to win by six points instead of by four. In abstract, yes, this still ruins the integrity of the game, but on purely outcome-based analysis what has he really changed? (If, on the other hand, he needed the home team to win and did something corrupt to cause the home team not to lose...)
As for catching the cheats: You may remember the chapter in Freakonomics about suspicious results in sumo wrestling. Couldn't one design a similar study involving, say, NBA games with a final score within 2-3 points of the spread? (Or within 2-3 points of the over/under?)
Unless players, coaches, and refs were chronically acutely aware of the exact spread, you wouldn't expect much discontinuity in stat trends involving games barely on either side of the line. (You would expect bits and pieces of discontinuity between games some team barely lost and games it barely won.)
Some interesting questions:
1. For all NBA referees, what was the average distribution of fouls in games in which
a) a home underdog barely covered?
b) a home underdog barely failed to cover?
c) a home favorite barely covered?
d) a home favorite barely failed to cover?
2. For NBA referee X, what were those distributions?
3. For all NBA refs, on average how many fouls were called in games in which the teams {barely hit, barely missed} the over?
4. For NBA referee X [...]
Here's the only Freakonomics post I could find that mentioned the scandal. Somebody mentioned the difficulty of detecting a cheating ref whose actions could nudge the outcome to either side of the spread. Well... just look for refs with a relatively high frequency of "outlier" games (e.g. visiting team got more foul calls than usual) correlated to close calls where the outlying trend worked to the benefit of whichever team barely covered.
Meanwhile Mark Cuban is an outstanding business leader. I should have guessed he would write something like this (but both the position and the eloquence still surprised me).
Posted by Matt Bruce at July 23, 2007 01:08 PMAlso, keep in mind that a lot of the discussion (though it was unclear if this is because it's what actually happened, or just as a hypothetical) was focusing on the over-under: it's a lot easier (and, to first order, less suspicious-looking) for a ref just to call a tighter or looser game on both sides.
Posted by: Paul at July 23, 2007 03:54 PMI certainly don't think that the institution of point spreads is or should be under attack. There's a knockdown pragmatic argument: people will bet on sports, in every way. They just will. Eliminating regulated point spreads will drive such betting underground (which is a Bad Thing, corruption-wise).
Speaking of: I think people are generally ignoring that some of the Donaghy-related betting could have happened underground. (One consequence: less documentation of how the spread moved. Another consequence: Donaghy now has to worry both about Big Vinnie from the mob and whatever goons the underground bookies employ.)
Posted by: Nate at July 23, 2007 09:55 PM