Anticipating line shifts in football betting: why lines move

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Football lines move for two main reasons: new information, such as injuries and weather, and bets from customers the book takes seriously. You can anticipate some moves by knowing when news is due and which side casual bettors usually back. The market adjusts quickly, though, so the practical goal is to bet when your number beats the market’s and to get the best price you can.

Why football lines move

News is the most obvious cause. A starting quarterback ruled out can move a spread several points, while a backup lineman usually won’t move it at all. Wind forecasts move totals more than spreads. Our guides to injuries and the point spread and betting and weather cover both in detail.

Bets are the other cause. Books adjust their numbers as money comes in, and they give more weight to some customers than others. A book may move after one bet from a customer it respects and barely react to many small bets from casual customers.

Most football spreads don’t move far. In the football line data economist Steven Levitt used for a 2004 paper, the spread posted on Tuesday was within one point of the kickoff spread in 90% of games. When a line did move, 85% of the moves were half a point.

How closely a game is watched matters too. A study of NFL lines from 2007 to 2021 found more frequent and larger moves in games that drew less public attention. The authors suggested oddsmakers spend more of their time on the most visible games.

Sharp money and public money

“Sharp” is betting slang for well-informed bettors whose opinions a book respects. “Public” money means casual bettors, who tend to back favorites and well-known teams. In a handicapping contest Levitt studied, 60.6% of picks went on favorites.

Books pay closer attention to sharp money because it’s more likely to be right. Levitt described the risk this way: “If bettors are able to recognise and exploit mispricing on the part of the bookmaker, the bookmaker can sustain large losses.”

Books also don’t always try to balance the money on each side. In Levitt’s contest data, at least two-thirds of the picks fell on one side in almost half of games, and he concluded that books set prices to take advantage of bettors’ biases.

You’ll often see a “reverse line move,” where most bets are on one team but the line moves toward the other. It can mean respected money is on the less popular side. The betting percentages behind it often come from one book or an unnamed source, so treat them with caution. Our guide to reverse line moves explains the idea using baseball.

How limits affect line moves

Every book caps how much you can bet at a given price. A study of NFL line movement notes that these maximums let books avoid taking huge bets at one number. A large bettor has to split a bet into smaller pieces, and the book can move the line between them.

At Bovada, limits vary by event, and requests to bet more than the limit go to its Book Managers for review. Its terms also say it can reject any wager, and that professional players, along with players it thinks are abusing its bonuses or wager limits, “may have wagers voided.”

When to bet early and when to wait

Start by knowing when the news comes out. Under the NFL’s injury report policy, teams post practice reports on Wednesday, Thursday and Friday before a Sunday game, and give injured players a game status (out, doubtful or questionable) by 4 p.m. Eastern on Friday.

For a Monday game that status report is due Saturday, and for a Thursday game it’s due Wednesday. Clubs hand in their inactive lists at a meeting 90 minutes before kickoff.

If your number is based on something the market hasn’t reacted to yet, such as a forecast for strong wind, betting early gets you the price before it moves. If your bet depends on news that isn’t out yet, such as whether a star will play, waiting costs you some price but saves you from betting blind.

An old rule of thumb says to bet favorites early and underdogs late, on the theory that public money pushes favorites’ prices up during the week. That can happen, but it doesn’t always. A line can just as easily move toward the underdog if bettors the book respects take it.

Watch the key numbers. In the NFL, 3 and 7 are the most common final margins, so a move from -2.5 to -3.5 matters more than a move from -4.5 to -5.5. If you like the favorite at -2.5 and expect the line to reach 3, there’s a good case for betting early.

Line shopping

Books don’t all move at the same moment or to the same number, so compare prices before you bet. Small differences add up. At -110 you need to win 52.38% of your bets to break even, and at -105 you need 51.22%.

Say you win 52 of 100 bets, each set to win $100. At -110 you risk $110 a bet and finish $80 down: 52 × $100 minus 48 × $110. At -105 you risk $105 a bet and finish $160 up.

Closing line value

Closing line value (CLV) compares the price you got with the last price before kickoff. If you bet a team at +3 and it closes at +1.5, you beat the closing line by 1.5 points. The closing line reflects all the news and money that came in after your bet, so beating it regularly suggests you’re getting good prices.

For moneylines, compare probabilities. Say you bet an underdog at +130, and it closes at +110 with the favorite at -130. Those closing prices imply 47.62% and 56.52%, which add up to 104.14% because of the book’s margin. Divide the underdog’s figure by 1.0414 and the market’s closing estimate is about 45.73%.

Your +130 needed only 43.48% to break even (100 ÷ 230). If the closing estimate is right, your bet is worth about $5 per $100 on average: 0.4573 × $130 minus 0.5427 × $100.

CLV is useful because results are noisy. A bettor who truly wins 55% of the time at -110 would still finish below 52.38% over 100 bets about 31% of the time, and over 500 bets about 11% of the time. CLV gives you a read on your prices much sooner.

It has limits. The closing line can be wrong, and a small move in your favor may not cover the book’s margin. Say you bet +3 at -110 and it closes at +3 -115, with the other side at -105. Remove the margin and the closing price gives your side about a 51.1% chance, which is still short of the 52.38% you need at -110.

Track the line you got and the closing line for every bet. Over a season, it tells you more about your process than your win-loss record. Our guide to the three handicapping techniques of football covers building your own number to compare with the market.

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Bovada posts NFL spreads, totals and moneylines through the week, so you can compare its prices with other books and watch how its lines move. If you live in a state with legal online sportsbooks, a state-licensed book gives you more protection, because it answers to a state regulator if something goes wrong.

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