A lot of different things could happen in the N.F.L. conference championship games on Sunday.
But oddsmakers are pretty sure what is likely to happen. The New England Patriots will beat the Pittsburgh Steelers by about 6, and the Atlanta Falcons will defeat the Green Bay Packers by 4 or 5 in a high-scoring affair.
One of the truisms of gambling is that it is difficult for a team to be a great bet week in and week out. That’s because the more a team wins and covers the spread, the higher its spread will be the next week and the week after that. Eventually, most teams congregate close to .500 against the spread for the season.
That makes this season for the Patriots all the more remarkable. Despite being favored in 15 of 16 games by as many as 17 points, the Patriots finished 13-3 against the spread, earning a tidy profit for those who bet them blindly. That was the best record in the league.
It seems hard to remember, but in Week 1, the Patriots were 8½-point underdogs to an Arizona Cardinals team that had impressed last season. Part of that gap was no doubt attributable to the status of quarterback Tom Brady, who was sitting out the first game of his four-game suspension for his role in the scandal involving the deflation of footballs.
The unheralded backup Jimmy Garoppolo was up to the task, though, and the Patriots won in an “upset” that later events proved wasn’t so much of one. The Cardinals finished 7-8-1.
Favored in every game for the rest of the season, the Patriots won 14 of 16 regular-season games and covered the spread in 13 of them. The only time they did not was in Week 12, at the Jets, when the spread was 9½ and they won by 5.
The Patriots more than made up for that four weeks later when they faced the Jets at home and were stuck with their biggest spread of the season, 17 points. Bettors reluctant to lay so many points were burned when the Patriots romped to a 41-3 win.
By the time of the playoffs, the bookmakers were well aware of the Patriots’ tremendous record and posted a huge number, 16 ½, for their game against the Houston Texans. The line seemed somewhat insulting to Houston, which, after all, had won its division and beat the Oakland Raiders in the wild-card round. But the Patriots covered again, winning by 18.
Before you mortgage your house to bet on every Patriots game next season, be aware that trends like these seldom last more than a year. Last season’s best team against the spread, the Minnesota Vikings, at 13-3, did post a winning record again this season, at 9-7. But the Cincinnati Bengals, who were 12-3-1 in 2015, staggered to a 6-9-1 record against the lines this season.
N.F.L. games this season averaged a total of 45.6 points scored. So the bookmakers’ over-under of 51 on the Patriots game indicates they expect it to be somewhat high scoring. But it should be nothing compared with the Falcons-Packers game, which has a whopping over-under of 61 points.
That’s the highest over-under ever for a playoff game, Bookmaker.eu reports. The previous high was 59.5, for the 2011-12 wild-card round between the New Orleans Saints and the Detroit Lions. (They scored 73 and went over.)
The highest regular-season total came in 2000 between the Rams and the San Francisco 49ers. That total closed at 61.5, and the teams combined for 58 points, just going under. “Bettors perceive these teams as two of the most potent, pass-happy teams in the league, and they witnessed them score 65 points in a Week 8 shootout,” Scott Cooley of Bookmaker.eu said.
He also noted that “football rules have changed to enable more scoring.” He added: “The quarterbacks and pass catchers are protected in a way they weren’t in the past. We are also seeing more pass interference calls with the new rules that cater to the offense.”
Big over-under totals are often not big enough. Oddschecker reports that of the 10 highest totals in history, eight ended up going over.
In general, totals for college and N.F.L. games have been creeping up every year as high-powered offenses increasingly dominate. The Falcons led the league in scoring at 33.8 points per game, and the Packers were fourth at 27.0. The two teams have gone over in all three of their playoff games this season.
If the game ends 14-7, regardless of who wins, we’ll have the biggest surprise of the season.
An earlier version of this article misidentified the home city of the 2000 Rams. While they now play in Los Angeles, the Rams played in St. Louis at the time.