2024 NFL Season, Week 1: What We Learned from 49ers' win over Jets on Monday night

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• REWATCH: Jets-49ers on NFL+
• READ: Mason's 147 yards power CMC-less Niners to win

1. Mason comes through in McCaffrey's absence. Christian McCaffrey's appearance on the inactive list came as a bit of a surprise, as he'd been listed as questionable with a calf and Achilles ailment prior to Monday, and left many wondering how the 49ers might adjust without him against a Jets team known for having a stingy defense. In the end, we shouldn't have worried at all, because if there's any coach who will maximize production from lesser-known running backs, it's Kyle Shanahan, who inserted Jordan Mason into his offense and watched him flourish. Mason finished with 147 yards and a touchdown on 28 carries, powering a 49ers offense that rode the ground game to a dominant advantage in time of possession (38:40 to 21:20), and peppered New York's defense with a collection of Brock Purdy passes to six different targets. Make no mistake: The star of the night was Mason, the latest running back to rise from irrelevance into a prominent role, joining the likes of Raheem Mostert, Elijah Mitchell, Jeff Wilson, Matt Breida and others, even if only for one night.
2. Jets' defense crumbles. For most of the Robert Saleh era, New York has hung its hat on its defense. It's been the Jets' saving grace while they've floundered without a legitimate quarterback. But for the first time in recent memory, the Jets' defense failed to show up Monday night, allowing the 49ers to rack up 401 yards of offense and string together an astounding amount of lengthy drives. Five of San Francisco's nine possessions lasted nine plays or more, and four of them covered at least 70 yards. The most surprising detail in this? The 49ers didn't need to convert on third down a lot to keep it going, finishing 6 for 13. The 49ers schemed better than the Jets, appearing one step ahead of New York from the second quarter onward, and executed better than the Jets, who struggled to mount much of a pass rush (10 total pressures) without holdout Haason Reddick and rarely had an answer for whatever Shanahan was cooking up.
3. Kyle Shanahan starts 2024 on a roll. If the time of possession advantage didn't tell you enough, just watch one of the 49ers' eight straight scoring drives for proof of how deep Shanahan was in his bag Monday night. The expert play-caller had full control of the game from San Francisco's third possession onward, mixing in a number of different run concepts while also causing headaches for New York's pass defense. The peak was beautiful for true football nerds. After Purdy missed a wide-open Kyle Juszczyk running down the sideline, Shanahan dialed up a wheel route for the fullback, who exited the backfield through the B gap and found a soft spot between defenders for a 34-yard reception down the left sideline midway through the third quarter. At that point, it became obvious the Jets wouldn't find an answer for Shanahan, whose mastery of his own offense was on full display and helped the 49ers cruise to an emphatic season-opening win.
4. Rodgers gives preview of what Jets could be. The fourth play of the season must be bad luck for Aaron Rodgers, who saw his 2023 season end on the fourth snap and watched Breece Hall fumble away possession on their fourth snap of Monday night's game. Lesser teams might struggle to overcome an early setback such as this, but not Rodgers, who immediately rebounded, leading a well-balanced 12-play, 70-yard drive that included two third-down conversions on completions to Garrett Wilson and ended in a Hall touchdown run from three yards out. The march was so impressive, social media lit up with claims it was the best Jets possession of the last 10 years, if not longer. Hyperbole aside, it certainly was impressive and suggested we might be in for a barnburner between two heavyweights. Ultimately, we learned it was merely a glimpse of what the Jets' offense could look like with Rodgers at the controls, as a lack of execution (two straight three-and-outs followed) hurt their ability to control possession, and by the time they had another legitimate chance to put something together, a 16-point deficit threw a wrench into whatever offensive coordinator Nathaniel Hackett might have had in mind for the offense. Still, it was a nice peek at what Rodgers -- who was only afforded 21 passes Monday night -- could produce with the Jets. We'll see if it becomes more frequent in the weeks ahead.
5. New York has its measuring stick. The Jets started 2023 with an extreme amount of fanfare and watched it evaporate after four plays. This time around, Rodgers made it through the game without incident, and although he threw an interception in the second half, he still gave Jets fans crumbs of what could end up being a delicious dessert. One thing is certain, though: The Jets need to be better on defense, which was once their calling card and failed to show up Monday night. Reddick's absence was noticeable, and perhaps this result will spur some action regarding his contract-related holdout. Even if it doesn't, the Jets now know what it is like to take their talents and stack them up against an elite NFL team -- and they learned they aren't there yet. Luckily, Week 1 is the best time of the season for this lesson.

Next Gen stat of the game: Niners left tackle Trent Williams didn't allow a single QB pressure on 33 pass-blocking snaps, his first game without allowing a pressure on at least 14 pass-blocking snaps since Week 2 of the 2022 season. 

NFL Research: Shanahan's 49ers successfully played keep-away Monday night, dominating time of possession 38:40 to 21:20. The Jets' 21:20 with possession was the lowest mark in any game in Aaron Rodgers' career.