A betting line and what it represents is rather mundane and straightforward to most bettors: they log onto their book, take a glance at the lines, and make their bets. The reality is that those lines actually represent an evolving and nuanced market deserving of more attention from bettors.
This is especially true for the NFL, as the lifetime of a line for any given game spans nearly two weeks whereas in other sports a line may be on the board for 24 hours at most.
In the NFL, the chronology of a line usually looks something like this:
- Lookahead lines open the Tuesday or Wednesday the week prior to those games
- Lookahead lines close as Sunday's games kick off
- Lines reopen as the Sunday afternoon slate concludes
- Lines take shape Tuesday through Sunday morning
- Lines close as each game kicks off
But why does this matter? Why should we care? Quite simply, football is flawed fundamentally. Teams play one game per week and just seventeen games in a season. Those games are also subject to incredibly high levels of variance given how much win probability is distilled into a handful of plays in each game, whether it's turnovers or a few high-leverage third and fourth downs. Yet despite this, bettors for the most part largely remember results as presumably earned wins or losses and/or whether a team was able to cover or not.
And because bettors tend to remember game results in such a binary and rigid way, crowd-sourced narratives tend to echo loudly in the lead up to the following week and books can make anticipatory adjustments between the closing of lookahead lines and reopening of that line during game-week to help cushion anticipated liabilities.
For example, books can rather easily and expectedly know where money may flow into when Sunday evenings from last season were full of narratives such as "Mike McCarthy is an idiot, he always loses games due to his clock management" or "The Steelers' offensive line might be the worst in the league this season, they have to be an autofade" or "The Panthers are the worst team in the league, how can anyone back them?".
But those teams went a combined 31-22 against the spread last year, good for a 58.5% cover rate - a rate most bettors would dream of hitting. These market inefficiencies caused by the discrepancies between the actual and perceived merit of teams provide an opportunity for more savvy bettors. Reading the market and anticipating moves can help bettors time the market better and make more winning bets.
To help illustrate this, pro sports bettor Adam Chernoff of “The Simple Handicap” podcast sat down to discuss how he uses market shifts — from lookahead to reopen and reopen to close — to identify potential value:
Q: When evaluating significant line moves from lookahead to the opening of game-week lines, how do you determine what is signal and what is noise?
First thing is looking at injuries. Lookahead lines come out on the Tuesday/Wednesday the week prior, and a lot can happen between then and Sunday injury-wise. The injuries can be divided up a couple of ways:
1. There can be guys that get hurt in the game on Sunday that would then move the line at reopen. For example, Lamar heading into Week 15 vs. Green Bay: it was +2.5 on the lookahead, reopened +7 on Sunday when it was assumed he would be out, and now is back to +4 with news that he might play.
2. There can be guys that get hurt (or ruled out because of COVID) that are never accounted for in the game result. For example, Odell Beckham Jr. just tested positive for COVID, which brought the line for Week 15’s game against Seattle from +6.5 down to +5.5. But what about next week’s line for the game against the Vikings? How does the lookahead line, which comes out mid-week, reflect his absence seeing as how that line will then reopen at a different number on Sunday following the results of Week 15’s game?
Second thing is looking at box scores and performances upon the reopen. NFL odds are impacted by what bettors saw last more than any other sport because it is the one sport where the public does have a say. For that reason, seeking out misleading box scores is important since lines will always adjust based on performance within the box score.
For example, in Week 13 the 49ers lost to the Seahawks 30-23. Despite this, they opened as +1 underdogs against the Bengals for Week 14 and quickly moved to a -2 favorite. This is because in their loss to SEA, SF was nearly two yards per play and five yards per pass better. Can there be more that is driving a move like that? Sure, but generally, a misleading result like the 49ers’ performance in Week 13 will lead to a position going the other way.
Q: So injuries and misleading results can drive some of these moves from lookahead to reopen. Are there other reasons a lookahead line might be off and move when it reopens?
Yes, let’s use Week 15’s New England-Indianapolis game as an example — which was off, in my opinion. It opened at Indianapolis +2.5, so I bet it for $500. Five minutes after the bet was made, the line became a pick ’em, and that’s where the lookahead line would close at. But this game was unique with both teams coming off of a bye, so when the line reopened Sunday evening at the same pick ’em the lookahead landed on and closed at, you can isolate that movement as one caused strictly by money coming in.
Q: On “The Simple Handicap,” you often compare lines by using common opponents or similarly tiered teams, as well as using closing lines from previous matchups of the same teams. Can you demonstrate how that works?
In the end, this is a market. The perception people have of teams always changes more each week than the teams change themselves (outside of injuries, of course). The Week 12 and Week 14 Baltimore-Cleveland games are a good example. In the first game, Baltimore opened -6 as the home team, but by kickoff, it was bet down to Baltimore -3. Baltimore went on to win 16-10, but they turned the ball over four times, got outgained in yards per play — the game was just a mess.
In Week 13, Baltimore loses to Pittsburgh 20-19 while Cleveland is on a bye. So you have Baltimore coming off a loss, Cleveland coming off a bye, the game being played in Cleveland this time, and the last matchup being misleading. Despite this, the line opened at Baltimore -1.5. At that number, of course, it was going to get bet — and it did, and it ended up closing Cleveland -3.
Same thing happens with divisional matchups over a longer stretch too. In Week 3, LA Chargers at Kansas City opened at Chiefs -7 and was bet down to Chiefs -6. Kansas City shut down Chargers for three quarters but then the game got crazy late with LA winning off of a fourth-down conversion, a turnover, and a late drive. They play again in Week 15, but LA is now home, and the line opened Kansas City -3.
What do you give Kansas City for home-field advantage, 1.5 to two points maybe? How much for LA, no more than 0.5? So going off of the Week 3 close of Chiefs -6 we should be around Chiefs -4, but it opened Chiefs -3. So the line has moved slightly against Kansas City. But in the time since Week 3, how have these teams changed? Kansas City transformed their defense (which was their biggest issue early in the season), while the Chargers have more or less stayed the same. So it was no surprise to see that line move from Chiefs -3 to Chiefs -4 quickly. Granted, there are now COVID issues with the game, so the matchup is a free-for-all now, but you can see how a move could have been anticipated prior to that.
So to summarize:
• The perception of teams changes faster than actual teams do, causing inefficient moves when lines reopen on Sundays.
• Although the impact injuries have on lines is the easiest to observe, they can be understated in the following week’s lookahead lines due to the uncertainty and/or short-term nature of those injuries.
• Identifying misleading results (turnovers, late-down conversion rate, injuries, etc.) in matchups can help spot unwarranted line moves at reopen.
• Using the closing line from a previous matchup between two divisional teams while adjusting for context and situation can reveal if a current line is off and if it should move.
• Using these skills can help you time the market better and get the best number possible.