Table of Contents

1. The four down-by-down lines
2. San Francisco won second down and it wasn't close
3. The Rams, oddly, were the anti-2025 Rams on second down
4. Seattle lost second down and won anyway (see: three interceptions)
5. What to watch as the sample grows

The four down-by-down lines

Every non-special-teams play from both games, split by team and down:

For scale: across the entire 2025 regular season, the league averaged +0.021 EPA/play on second down at a 45.2% success rate. Both winners lost first down in EPA terms. Only one of them turned second down into a competitive advantage.

San Francisco won second down and it wasn't close

Twenty-three second-down plays, +0.602 EPA/play, 73.9% success. That is not a normal number. San Francisco's own 2025 second-down baseline was +6.9 EPA per 100 plays and 47.8% success — good, not spectacular, and roughly a tenth of what they produced on Sunday. Every team's number moves around in a 47-snap sample, but a leap of that size is the game-story, not an artifact.

The downstream effect is where the story actually lives. San Francisco's average yards-to-go on third down was 3.2 — for context, the Rams sat at 5.8, Seattle 6.7, and New England 6.4. Seven of San Francisco's twelve third downs were short-yardage (≤3), and they converted four of those seven; overall they went 7-of-12. When your second-down menu is that productive, third down stops being third down. It's basically an extension of the drive.

Two of the second-down conversions were touchdowns — Demarcus Robinson on a 2nd-and-6 deep middle for 39 yards, and Deebo Samuel on a 2nd-and-8 for 15 — but the more revealing entries in the play log are the routine ones. On 2nd-and-4, 2nd-and-5, 2nd-and-6 through the middle innings, Brock Purdy kept finding McCaffrey, Kittle, or a scramble lane for enough yardage to move the sticks or set up 3rd-and-1. That's the mechanism: the down became a stick-mover, not a break-glass down.

The Rams, oddly, were the anti-2025 Rams on second down

The team that got flattened on second down in this specific game was the team that ranked as the best second-down offense of these four in 2025. Los Angeles' 2025 second-down mark was +18.5 EPA per 100 plays at 57.8% success, easily the best of SF/SEA/LA/NE. On Sunday they were −0.246 EPA/play and 42.9% success on 21 second-down snaps, and that dropped them into 2-of-9 on third down at an average of 5.8 yards to go, including four third-and-shorts they went 2-of-4 on.

Read that gap however you want — one game, one opponent, in September. My read is that it's the loudest single-game caveat in the piece: the largest 2025-to-2026 second-down swing among these four teams belongs to the team the sample says the least about, because their baseline is the highest. Wait a few weeks before deciding anything is broken.

Seattle lost second down and won anyway (see: three interceptions)

Seattle is the interesting counter-case to the SF story. They actually won first down — +0.229 EPA/play, 52.4% success on 21 snaps — and then gave it back on second down (−0.161 EPA/play, 28.6% success on 14) and third down (2-of-11, average distance 6.7 yards). Only two of their eleven third downs were short-yardage, and they converted neither. The offensive down-and-distance chain was a mess.

Seattle won 13-10 anyway because the defense produced three interceptions and held New England to −7.35 total EPA on 67 offensive plays. New England's own down-by-down line was negative across the board — nothing on first (−0.093), nothing on second (−0.176), a disaster on third (−0.336) — and Drake Maye's offense couldn't get out of its own way long enough to press the Seahawks' shaky third-down defense.

What to watch as the sample grows

• Does San Francisco's second-down explosion persist past one opponent? A +0.602/74% game is not a repeatable rate — nobody's is. Whether they're closer to +0.10 or +0.30 across the next three weeks will tell us whether the play-caller's menu genuinely changed or the Rams' defense happened to serve up mid-down looks that Purdy sees in his sleep.
• Do the Rams look like the 2025 Rams on second down again in Week 2? If they climb back to something like +0.10 with a healthy success rate, Sunday reads as one bad script against a real front. If they don't, that's when it becomes a story.
• Does Seattle's offense keep landing in 3rd-and-medium? They avoided punishment for it by cashing in three New England turnovers. Sustaining a 2-of-11 third-down rate is a formula for losing games where the defense doesn't hand you the ball back.