49ers, Week 1 — What Repeats: Light Boxes Fell to One in Five

The San Francisco defense showed six or fewer defenders in the box on six of the Rams' 27 charted designed runs on Thursday night. 22 percent. Across all of last season this defense showed a light box on 83 percent of the designed runs it faced — 322 of 386 — with an average of 6.1 in the box. In Melbourne the average was 6.9. Read it in the Rams' terms and they saw the fourth-smallest share of light boxes of any offense this week, 20-ninth of 32, against a league median near 47 percent. This is the largest single change in the pack, on either side of the ball, and box count is at least partly the defense's call. A year ago this unit showed a light box on four designed runs out of five; on Thursday, about one in five. The Rams' 27 designed runs gained 114 yards anyway.

What the Rams' throws looked like against it: Matthew Stafford's 25 throws came out 14 catchable, 56 percent; the Rams' team rate of 54 percent was 30-first of 32 offenses in Week 1. Three of his 25 were charted interception-worthy — balls a defender should have caught — 12 percent, and the Rams' team rate of 10.7 was the highest of any offense in the league this week, not tied. Stafford was intercepted once, by Renardo Green, and the charting does not say whether that was one of the three. Against this defense across all of last season, opposing quarterbacks were catchable on 73 percent of throws and interception-worthy on 2.4 percent. And San Francisco did it while rarely sending more than four: five or more rushers on four of the Rams' 29 dropbacks, 14 percent, thirtieth of 32 defenses in Week 1 against a median of 27, and down from 22 percent last season. A charted blitzer came on two dropbacks. 4.2 rushers per dropback on average. Whether that is a unit or a Thursday is the season's question, and the Recap asked it first.

On offense the number that is new is motion. San Francisco put a man in motion on 51 of 75 charted plays — 68 percent, the highest rate in the league in Week 1, a hair ahead of the Chargers, against a league median of 45. Last season it was 56 percent, so this is up 12 points on an offense that already used it on more than half its plays. Screens went with it: seven of 36 dropbacks, 19 percent, against six percent of dropbacks last season. No-huddle, zero snaps. Play-action, on the other hand, did not move, and it gets a sentence because it is where everyone will look: eight of 36 dropbacks, 22 percent, fifteenth in the league with the median at 21, and 22 percent across all of last season. Brock Purdy's eight play-action throws produced five completions for 26 yards; his 26 other throws produced 20 completions for 179. The scheme change on Thursday was pre-snap movement and the screen game, not the fakes.

The ball charting on Purdy reads like a quarterback who rarely threw into traffic. 29 of his 34 throws were catchable, 85 percent, fourth-highest among the 32 offenses this week and 10 points over his own 76 from last season. Two of the 34 were contested — a receiver and a defender arriving together — six percent, against 16 percent for Purdy across last season. Two of the 29 catchable balls were dropped. No throwaways. The counterweight: two of the 34 throws were charted interception-worthy, six percent, sixth-highest in the league this week, and Purdy was intercepted once, by Quentin Lake at the Rams' 31; the pack does not say whether that was one of the two. Last season the rate was just under four percent, 11 balls on 287 throws. So the accuracy went up, the traffic went away, and the loose throw did not.

The run game went into heavy boxes and came out as the offense's best unit. The Rams showed a light box on 10 of San Francisco's 28 charted designed runs, 36 percent, 20-fourth of 32 offenses this week; last season this offense saw light boxes on 63 percent of its designed runs, with an average of 6.4 in the box against 6.8 on Thursday. Those 28 designed runs gained 148 yards. The Recap had the run game as the offense's best unit by expected points; the charting adds that it did it into a heavier box than it was used to — 6.8 against 6.4 — which is not the easy explanation.

The stat lines have settled, so here they are, scored half-PPR. Purdy led the team with 21.1 — 25 of 34 for 205, three touchdowns, one interception, +5 carries for 29. Deebo Samuel caught six of seven targets for 48 and a touchdown, and took one carry for 12, 15 even. Mike Evans six of seven for 49 and a touchdown, 13.9. Demarcus Robinson two catches on three targets for 50 and the third touchdown. Christian McCaffrey ran 10 times for 68 and caught five of eight targets for 20, 11.3; Kaelon Black ran 14 times for 65. For the Rams, Kyren Williams ran 11 times for 41 and the touchdown and caught three for 24, 14 even; Puka Nacua caught five of nine for 74; Blake Corum ran 10 times for 54; and Stafford finished 15 of 25 for 155, no touchdowns, one interception.

A note on what all of that is measured against, because the show's name promises something it cannot deliver yet. There are no prior weeks of this 49ers team, so nothing above compares San Francisco to itself this season. Every baseline is all of last season — a different roster in places, a year older, in some places a different job. That comparison is good at one thing: it finds what was unusual about Thursday. It is no good at the other thing, which is telling you what is true. The within-season version of this show, the one that holds the 49ers against their own recent weeks, starts working around Week 4, and until then we will say each time which comparison we are making.

The season-long thread starts here. The Recap put down last season's ranks: a defense 20-fourth in expected points allowed per play and 20-ninth in the rate of plays it allowed to succeed; an offense sixth, first on third down, 20-first running the ball. The charting adds three lines. The defense went from light boxes on 83 percent of designed runs to 22, mostly rushed four or fewer, and the offense it faced posted the highest interception-worthy rate in the league — if the box counts hold, that is a pattern, and patterns repeat in a way Thursdays do not. The offense ran motion and screens well over last season's rates while play-action sat where it was. And the run game got 148 yards on 28 designed runs into heavier boxes than it saw all last year on average, from a unit ranked 20-first a year ago. We are not calling any of it. We are writing it down.

That's your 49ers — every game, by the numbers. This is Muffed: we do the same deep dive for all 32 teams. Follow the 49ers show wherever you're listening, so next week's recap lands the moment it's out. No theater. Just the football.

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_Data via nflverse. Charting: FTN Data via nflverse._