The Patriots won again; Tony Romo and the Cowboys prevailed in another last-minute comeback; and Philip Rivers threw for another thousand yards — by historical standards, Week 1 of the 2015 NFL season didn’t offer much in the way of surprises. According to our Elo power ratings, 75 percent of this year’s season-openers were won by the pregame favorites — the seventh-best opening week for favorites in the half-century of the Super Bowl era. Yawn.
But wait! Something radical did happen: The Tennessee Titans, who finished last season as the worst team in football, blew somebody out. The Titans (led by rookie quarterback Marcus Mariota) crushed the Tampa Bay Buccaneers (led by rookie QB Jameis Winston) 42-14, and it caused their Elo rating16 to shift drastically: Their 45-point gain was the 13th-biggest opening-week Elo spike of the Super Bowl era. That’s the equivalent of Tennessee’s weekly Vegas point spread increasing by an average of 1.8 points per game over the remainder of the season. Just one win and the Titans got 2 points better. Not bad.
Going into the game, Elo predicted the Titans to win 5.2 games this season; now it thinks they will win 6.7, all because of the big Week 1 win. If you’re counting at home, that’s a difference of 1.5 wins. About 0.6 of that was due to winning the game itself (Elo said they had a 36 percent win probability going in), but the other 0.9 is because a higher Elo rating makes them more likely to win future games.
To pump the brakes a bit: Yes, Tennessee’s Elo rating is still just 1385 — fifth-worst in football. But modern NFL history17 says a great coming-out party in Week 1 can mean (slightly) greater things down the line. Although the relationship between a team’s Week 1 ratings boost and its subsequent Elo gains is small, it’s also statistically significant — which could mean Tennessee’s rebuild is on a slightly accelerated schedule.
Teams as bad as the Titans were last year tend to improve only modestly the following year because of natural progression toward the mean. But Tennessee’s opening-week Elo hike was two standard deviations better than the overall NFL average since 1966. Historically, such an extreme performance is associated with a gain of about 54 additional Elo points over the remainder of the season — the kind of boost that would put the Titans’ Elo rating at 1439 by season’s end.
While still below average, that number would position Tennessee much closer to respectability than we’d have expected after last season’s 2-14 nightmare. Simply knowing the Titans had a 1256 Elo at the end of last year,18 we’d have predicted them to finish this season with a 1344 rating — nearly 100 points shy of the 1439 mark suggested by their opening-week performance. For a franchise that hasn’t legitimately contended since the 2010 season, even this kind of a hint at progress is a refreshing development.
Read more: 2015 NFL Predictions