Week 6 TNF Seahawks-49ers: Advanced Review
49ers regain their rightful spot at the top of the NFC West, closing the door on what could have been another improbable loss
The adjusted scores quantify team play quality, with emphasis on stable metrics (success rate) and downplaying higher variance events (turnovers, special team, penalties, fumble luck, etc). Adjusted expected points added (EPA), in conjunction with opportunity-based metrics like total plays and drives, projects adjusted points. Adjusted scores have been tested against actual scores and offer slightly better predictive ability, though their primary benefit is explanatory.
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Find previous advanced reviews here
** Adjusted Scores table:
“Pass” - Pass rate over expectation (based on context of each play and historical averages
“Success” - Success rate on offense, a key metric in adjusted score vs actual
“H & A” - Home or away team
SF-SEA
The 49ers had a dominant lead at halftime and, unlike some other games this season, held on all the way for the victory. Despite their slow start, the 49ers are now atop the NFC West at 3-3, though still well behind the 5-0 Vikings (plus not having the tiebreaker) in the race for the No. 1 seed in the conference.
The Seahawks failed to score in the first half until a late field goal, putting the 49ers ahead 16-3 and getting the ball first in the second half. With a 97% win probability following their first touchdown of the second half, you’d think the 49ers were in an ideal position. But their fan base was likely experiencing déjà vu (not the good kind), when the Seahawks took the subsequent kickoff 97 yards for a touchdown, as they’ve already lost multiple games this season with a similarly high win probability in the third quarter (96.7% against the Rams and Cardinals). The Seahawks were within a score multiple times in the second half, as late as the final two minutes, though the 49ers win probability never got below 75% in the second half.
By the fundamentals, the 49ers were the deserving winners, benefiting from a massive turnover advantage (+13.2 EPA), though the Seahawks were able to keep the game close with fourth down conversions (+5.8 EPA) and the kick return touchdown (+5.6).
Perhaps the Seahawks could have played to win and not “keep it close” at the end of the first half by going for the touchdown down 16-0, but instead took the three points. The win probability advantage going for the touchdown wasn’t huge in a absolute sense (+1.6%), as the benefits at the end of the half were mitigated by the lack of any “pin them deep” advantage if you fail.
But sometimes you have to look beyond the absolute numbers when these decisions come in very low-probability circumstances. A re-framing would be that a successful field goal only raised the Seahawks win probability from 3.2 to 4.3%, or a 1-in-23 chance to pull off the comeback. Making a successful touchdown would have raised their win probability to 9.1%, or a 1-in-11 chance to win. Accounting for conversion rates and the win low probabilities in all circumstances makes the decision look like more of a toss-up than it was, if your goal is to put yourself in a realistic position to win the game.
The 49ers translated their 50% offensive success rate into an extremely efficient 96th percentile efficiency, bolstered by two huge plays: the 76-yard touchdown pass to Deebo Samuel (+6.3 EPA) and a late 76-yard rush by the newest RBs-don’t-matter hero, fourth-round rookie Isaac Guerendo (+5.0 EPA).
The Seahawks made a few big plays in the passing game, but they were lower leverage with the score differential fairly high, and those gains netted out multiple interceptions to end at average dropback efficiency.
As the NFL’s previously most pass-happy team, the Seahawks coming off of multiple losses appeared focused on run-establishment in the first half, mostly to their detriment. They ran on six of their seven first downs in the first half, gaining 1.5 yards per carry and totaling -2.7 EPA. It’s no wonder that those low upside first-down runs anchored the offense early.
Another fantastic game for Brock Purdy, who only trailed Jayden Daniels in my adjusted quarterback efficiency metric through Week 5. Purdy continues to drive efficiency particularly well through the air, not relying on outsized YAC gains, as he had in previous seasons. Purdy had a perfect game avoiding negatives (zero sacks, zero turnovers), using his escapability multiple times to turn likely sacks into positive gains (+2.3 EPA on scrambles).
Geno Smith started slowly and was able to get back to even efficiency in the second half. Unlike Purdy, Smith mostly gained value via receiver YAC, and his sack and two interceptions took nine expected points off the Seahawks dropback passing value. These are the games that Smith peppers into the season that look better according to film hipsters than the general audience and numbers nerds. Smith hasn’t figured out how to match his perception as a potential top quarterback with the numbers. Smith is at 11th in EPA per play after this game, and he was 14th and 13th the previous two seasons.
