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Quarter-season stat check: How Brock Purdy and the 49ers offense stack up

A football player in a white and gold uniform stands on the sideline with a man in a white 49ers shirt holding a football, talking together on a stadium field.
Brock Purdy ranks as the league’s most efficient quarterback four games into the season. | Source: Michael Zagaris/Getty Images

One month is in the books for the San Francisco 49ers. It seemed effortless at times and tumultuous at others. The final result: a 2-2 record entering a two-game stretch against a pair of NFC West opponents that might truly set the tone for this 2024 season.

The numbers can help us make sense of the inconsistency and set the table for what the 49ers must do to strengthen their Super Bowl bid. We’ll focus on the offense in this piece, but for the sake of full context, let’s start with a league-wide comparison to last season.

Here are the 49ers’ ranks in expected points added (EPA) across all phases of the game.

Offensively, the 49ers — who’ve dropped from No. 1 to No. 6 — have been good, but not the top-ranked juggernaut they were in 2023. The absence of star running back Christian McCaffrey is the primary culprit here — more on that in a bit.

Defensively, the 49ers are at the same No. 10 spot they finished in last season after sandwiching poor games against the Vikings and Rams with good ones against the Jets and Patriots. We’ll look further under the hood of that and the special teams unit, which has regressed to a dead-last ranking, this week.

The 49ers offense led this team in 2023 and the same will likely be true in 2024. The Cardinals and their struggling 30th-ranked defense visit Levi’s Stadium on Sunday, so expect the 49ers to continue climbing the offensive rankings. No surprise, their biggest struggles so far have come against the Vikings, who rank No. 1 in defensive EPA through the first month.

We’ve already explored 49ers quarterback Brock Purdy’s torrid start. Stylistically, much has changed this season. The 49ers hope that McCaffrey’s return, when it does come, will lead to better red-zone efficiency. They paced the NFL with a 68% touchdown rate there in 2023. It’s dropped to 50%, good enough for No. 20, in 2024.

Numbers suggest the 49ers have the quarterback to improve in the red zone even before McCaffrey returns. Purdy, by metrics that adjust for bad luck like dropped passes, ranks as the league’s most efficient QB.

What’s happening in the run game to support Purdy is also promising, even though the 49ers’ overall efficiency there by EPA has dropped from No. 1 to No. 14.

In recent seasons, the offense had run much more frequently and effectively to the left, behind star tackle Trent Williams. But look at the division below. The 49ers appear to be developing a more ambidextrous rushing attack behind Jordan Mason, who ranks second in the NFL with 447 rushing yards at 4.9 yards per carry (YPC).

Those splits come from the Pro Football Focus database. The development of right tackle Colton McKivitz, whose PFF run-block grade has shot up nearly 20 points to 81.1, is paying off. So is the insertion of rookie right guard Dominick Puni. The 49ers are confident that the efficiency dip on the left side is temporary since Williams is playing back into shape following a training camp holdout.

Pass blocking is tricky to statistically gauge given Purdy’s changing style of play. Increased scrambling and a significantly higher depth of target — Purdy has gone from 8.1 to 10.6 yards (he now tops the league in that metric) — has contributed to the QB averaging 3.14 seconds from snap to release. That’s also the biggest number in the NFL.

It’s undoubtedly led to higher pressure numbers, but the data suggest that the 49ers’ offensive line is holding up well in protection given the circumstances. They rank No. 7 in ESPN’s cumulative pass-block win rate, which measures how often a line holds its blocks for 2.5 seconds or longer. Puni has upgraded the right guard position, while McKivitz (14 pressures allowed) and left guard Aaron Banks (9 pressures allowed) have scored the worst in pass protection.

Meanwhile, Purdy’s pass distribution has been radically different. PFF’s measure of yards per route run (YPRR), over a large enough sample, is a good way to gauge the efficiency of connections between a quarterback and various targets.

Brandon Aiyuk has statistically tumbled. His catch rate, which had steadily climbed from 62.5% in 2020 to 71.4% in 2023, is down to 52% this season. His per-game yardage output is half what it was in 2023.

The football has instead gone to Aiyuk’s fellow receiver Jauan Jennings, who’s leading the league in YPRR. Deebo Samuel has also seen a slight uptick, while tight end George Kittle’s efficiency has remained relatively constant.

A glaring change, of course, resides in McCaffrey’s data row. Until the versatile star returns, the 49ers will be missing a key outlet of production in their pass game. Because even though McCaffrey’s YPRR was lower than the team’s top wideouts in 2023, his space-making impact on the field — 49ers coach Kyle Shanahan has compared McCaffrey to Golden State Warriors superstar Steph Curry in this regard — is fundamentally important to the offense.

That’s why Purdy, though he’s remained successful, has had to strain harder for every bit of production. His tight-window throw rate, according to NFL Next Gen Stats, has nearly doubled. It was 12.8% in 2023 and is 24.6% this season. Despite this, Purdy scores near the top of the heap across efficiency metrics, while Mason has also rumbled to productivity. Significantly, he’s run well to both sides of the field. That balance will benefit a receiving corps that, despite Aiyuk’s slump to start the season, also isn’t lacking in firepower.

But the numbers are clear: There is still meat left on the bone for this good 49ers offense. The unit will almost certainly need McCaffrey to realize its full potential, but improvement can continue before then.

Perhaps receiver drop rate offers a good summation. In 2023, the 49ers finished with the league’s lowest drop rate, 1.9%. To begin this season, they rank at No. 15 — the middle of the pack — with 4.1%.

Sometimes, it’s as simple as catching the opportunities that present themselves. And for the 49ers, a more consistent job in this regard over September would’ve elevated their offense to another level.

October offers a chance to pick up that slack.

David Lombardi can be reached at dlombardi@sfstandard.com