Behind the Bets: The Zig Zag Theory

You're not betting the NBA properly until you know Zig Zag Theory

Updated: April 24, 2009, 8:52 PM ET
By Chad Millman | ESPN The Magazine
This is what every wise guy and bookmaker is thinking about once the NBA playoffs tip off: Zig Zag Theory.

It's not some late-night plan cooked up by bettors who owe too much, own too little and need to avoid getting pinched. It's a philosophy combining pattern recognition and bettor's logic (aka, insanity) that dictates how every spread is made and how every sharp bets pro hoops for the next eight weeks.

Getty ImagesIs he zigging or zagging?

The theory is pretty simple: If a team covers the spread in one game, bet against it to cover in the next. "You see a favorite that wins and covers, you would think they would be favored by more in Game 2," says my guy Scooch at the Orleans. "But they are almost always favored by less because other teams are expected to come out blazing."

Take a look at the patterns for the Heat-Hawks series. In Game 1, the Hawks were favored by five and won by 26. And yet, in Game 2, the spread actually dropped half a point, to Hawks minus-4.5. Most of the wise guy money came in on the Heat, and they easily covered. Same thing with the Mavs and Spurs. San Antonio was a 4.5-point fave in Game 1 and lost. But what happened in Game 2? The Spurs opened as a 5.5-point fave and got bet up by professionals to 6-point favorites. They won going away by 21.

Of course, the theory isn't foolproof. And the cat and mouse between bettors and bookmakers as they play Zig Zag is fascinating. Remember, bookmakers want to post a spread that makes people bet, not one that predicts the final point difference in a game. They know wise guys are going to consider the Zig Zag Theory when making their plays, so they need to decide how many points that is worth when making the spread. Is it one? Two? That can mean the difference between money earned and money lost.

Meanwhile, wise guys need to decide whether they're getting taken by inflated spreads. "I was betting the Zig Zag 30 years ago," one ornery, veteran wise guy told me. "Now the problem is the whole world knows about it and in most cases the line is overpriced. It is like betting into a stacked deck."

Take a look at the Pistons-Cavs series. In Game 1, Cleveland was favored by 11.5 points and blew out Detroit 102-84. But in Game 2, rather than using the 18-point win as a reason to increase the spread, bookmakers made the Cavs 11-point favorites. Then the wise guys bet so heavily on the Pistons the point spread dropped, from 11 to 10.5. Everyone expected the Pistons, down 1-0, to come out aggressive and desperate and, even if they didn't win, keep the game close. Of course, the bettors were wrong. Cleveland won Game 2 by 12, covering the opening line by just a point.

Same thing happened in the Magic-Sixers series. Even though the Sixers stole the series opener as nine-point dogs, bookmakers upped the number in Game 2, posting the Magic as 10-point favorites. "We just expected people to bet the Magic so we put up a high number," Scooch says. Sure enough, that's what happened. Then the Magic went out and won Game 2 by nine. The wise guys got suckered.

So, should you zig or should you zag over the next couple of days? I'm here to help, with a breakdown of the Friday, Saturday and Sunday games where point spreads are available:

Game: Cavs at Pistons, Friday

Current Line: Cavs minus-4.5
Here's another Zig Zag Theory rule of thumb: A series starts over when it changes locations. With the Cavs covering both games in Cleveland, I'd say stick with them in Detroit. Not just to win, but to cover.

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