Divisional underdogs went 1,359-1,252-74 ATS from 1999 through 2025: a 52.0% win rate over 2,611 decisions. That is the record. It is not proof that rivalry, familiarity, or coaching caused the covers.
Played regular-season games, one declared closing-spread convention, nonzero closes, seasons 1999–2025. The full cohort contains 2,685 games; pushes stay in W-L-P and leave the rate denominator.
The broad split
| Split | ATS record | Win rate |
|---|---|---|
| All divisional dogs | 1,359-1,252-74 | 52.0% |
| Road divisional dogs | 886-768-45 | 53.6% |
| Home divisional dogs | 473-484-29 | 49.4% |
| All non-divisional dogs | 2,091-2,046-115 | 50.5% |
The aggregate came from the road slice. Home divisional dogs lost more ATS decisions than they won. “Division dogs know each other” is too blunt to explain a split that changes that much by location.
Favorite and home-team views
Same 1999–2025 regular-season close query, read from the opposite side.
Divisional favorites went 1,252-1,359-74 ATS, a 48.0% win rate over 2,611 decisions. Home teams went 1,241-1,370-74 ATS, a 47.5% win rate; road teams went 1,370-1,241-74 ATS, a 52.5% win rate.
Favorite and home team are not synonyms. The snapshot contains 986 games with a home underdog and 1,699 with a road underdog. Positive spread_line makes the away team the dog; a negative value makes the home team the dog. Reverse that sign and you manufacture the opposite location result.
The spread bands did not carry the result alone
Same 1999–2025 query, bucketed by abs(spread_line).
| Divisional dog points | ATS record | Win rate | Outright wins |
|---|---|---|---|
| +1 to +3 | 468-425-38 | 52.4% | 425 |
| +3.5 to +6.5 | 452-422-8 | 51.7% | 282 |
| +7 or more | 439-405-28 | 52.0% | 175 |
The three rates sit within seven-tenths of a percentage point. That is sturdier than a headline produced by one tiny band, but it still describes historical cover decisions rather than a current ticket.
The path moved by era
Same cohort, split into fixed calendar windows.
| Window | ATS record | Win rate |
|---|---|---|
| 1999–2008 | 537-482-34 | 52.7% |
| 2009–2018 | 469-464-27 | 50.3% |
| 2019–2025 | 353-306-13 | 53.6% |
| 2021–2025 | 250-221-9 | 53.1% |
Annual rates were noisy: 63.4% in 2006, 40.2% in 2017, 46.2% in 2023, 56.4% in 2024, and 53.1% in 2025. The long window matters because one season can point hard in the opposite direction.
What the result can and cannot say
The CSV marks a game as divisional. It does not measure familiarity, staff continuity, quarterback experience against the scheme, or roster stability. Those are testable hypotheses, not columns hiding inside this count.
The clean claim is narrower: divisional underdogs covered more often than non-divisional underdogs in this closing-line snapshot, and the excess was concentrated on the road. The dataset also records 882 outright wins among the 2,685 divisional-underdog games; that moneyline outcome does not change the ATS record.
How to extend the record
Keep the rule fixed: regular season, div_game = 1, nonzero close, underdog side, and the same close source. Append new graded games. Report W-L-P before the percentage. Keep a missing close unavailable rather than turning it into a push.
For a current decision, use the NFL picks page and demand a current line. Use Analytics to reproduce the filter. The divisional betting guide supplies the weekly handicap; this post supplies the frozen count.
Where these numbers come from
How we counted: These numbers come from a frozen historical snapshot. We concatenated the NFL schedule CSV shards, kept played regular-season rows from 1999–2025 with div_game = 1 and nonzero spread_line, and graded the underdog against the closing spread. Positive ATS margin is a cover, zero a push, negative a loss. Cover rates exclude pushes. Source definitions and hashes are in DICTIONARY.json and manifest.json.
NFL ATS cover-margin distribution
Bars count completed NFL schedule rows by closing-spread cover margin using the repository canonical home-margin grading convention.
