Week 1 conclusions — analysis of the lasting themes and most important decisions in the San Francisco 49ers’ 32-19 victory over the New York Jets …

One game into the 2024 season, Brock Purdy has a passer rating of 89.9 and a Shanahan Rating of double extra thumbs up, which was as much for the things Kyle Shanahan didn’t see from Purdy against the Jets as for the things that he did.

The 49ers didn’t need Purdy to be reckless to win this game. In fact, reckless quarterback play was, by the early part of the third quarter, just about the only way the 49ers could lose this game on Monday night. And, for the 18th time in 22 starts with the 49ers, Purdy was perfectly good enough and sensible enough to help the 49ers to another victory.

Yes, the 49ers are 18-4 in Purdy’s regular-season starts from the end of the 2022 season to right now. That isn’t all because of him, of course.

But on Tuesday, Shanahan fully and pretty formally enunciated why even such a non-dynamic, mostly average Purdy performance like Monday is perfect for this coach and this team. And it has to do with winning the dang football game. Sort of important!

“Didn’t make any mistakes and made a number of plays with the ball,” Shanahan said of Purdy’s 19-for-29 outing, for 231 yards and no touchdowns or interceptions. “When they did have some pressure and stuff, he was able to get rid of it. When guys weren’t real open, he still made some really good, tight throws. Really only had one ball that he was aggressive on that got close to the defense where I thought they had a chance to pick it (a deep third-down pass attempt to Eric Saubert in the third quarter). Ultimately, probably wasn’t a great decision, but I could totally see why he did it. And I love that he didn’t hesitate and let it rip.

“That’s kinda how he played the whole game and only one got close to ’em. He played aggressive and played very controlled with a chance for us to win and not make mistakes. The way that game went, you get into the second half and truly felt the only way they could get back into it was if we had a bad turnover. And Brock was very trusting with the football — while still making plays.”

Aggressive, but controlled. Trustworthy with the ball, but still making the necessary throws. Shanahan has never produced a thesis paper for the baseline of what he wants from his quarterback, but he probably could just call up this game tape and say, “Right here.”

Now we all know that Purdy has had many spectacular games, too. He’s put up spectacular stats overall. He’s not a middling QB in any way. He’s got a high ceiling and, just a few years into his NFL career, it is going higher and higher. But it’s probably even more important to Shanahan, with this level of talent throughout the roster, that Purdy’s floor is so high, also. When the 49ers are in trouble, Purdy can jump in to save them. But when the 49ers are rolling, like they were on Monday, he’s sure not going to do something silly that saves the other team.

• Here’s a real stat: In his 22 NFL starts, Purdy has only had four full regular-season games with a passer rating less than the 88.8 he registered in his very first NFL start, in December 2022 against the Miami Dolphins. Three of those came last season, in the 49ers’ losses to Minnesota (81.5), Cleveland (55.3) and then Baltimore (42.6).

Which means Purdy’s 89.9 passer rating on Monday was in the bottom fifth of his career so far. And even so, it was a sublimely good QB game. Not a bad almost-worst-case scenario.

• I feel bad for Jordan Mason, who found himself in the middle of a controversy after his breakthrough, 147-yard game when he told ESPN that he learned Friday that he’d be starting this game. That immediately made the 49ers in general and Shanahan specifically seem like they’d been hiding the extent of Christian McCaffrey’s calf injury until they could spring his deactivation as a surprise a few hours before kickoff.

Maybe there was some 49ers gamesmanship involved, just to avoid tipping off old friend Robert Saleh until they absolutely had to. But I suspect it was much more about the coaching staff wanting to make sure Mason was emotionally prepared to play the full game if McCaffrey was out.

In the days leading up to the game, the 49ers could’ve presumed there was a 50 percent chance that McCaffrey would play. Maybe they figured it was 33 percent. But that’s all in the realm of the “questionable” designation on the injury report. And if there was even a five-percent shot that McCaffrey would be limited or out of this game, I can see the 49ers coaches telling Mason that this would be his game. They needed to believe he’d be ready for this. (Guess what: He was.) That was going to be the case whether McCaffrey was feeling good on Saturday and Sunday or not.

That doesn’t help fantasy league owners and bettors who got burned by the late scratch, and the NFL is increasingly tied to all of that. The 49ers are going to feel the heat on this one for a while. They could’ve been more transparent, for sure. But unless the 49ers’ leaders absolutely knew for a fact days in advance that McCaffrey wouldn’t play in this game, I think this is all explainable.

• More injury-report fun this week! Shanahan said Tuesday that McCaffrey is day-to-day for Sunday’s quick-turnaround game in Minneapolis. So there will be more guesswork. But even before his scratch on Monday, I wondered if the 49ers might just play it safe with McCaffrey and a few others on U.S. Bank Stadium artificial turf — with the big game against the Los Angeles Rams on the SoFi Stadium artificial turf coming up in Week 3.

And if the 49ers extend McCaffrey’s rest through the Rams game, he can return in Week 4 at home against the New England Patriots just in time for the stretch when the 49ers play four of five on the Levi’s grass leading into the Week 9 bye.

• The 49ers’ defense gave up some early yards and early points to Aaron Rodgers’ Jets offense, but after a few series, the 49ers shut down the Jets’ running game and made Rodgers look a little skittery against the 49ers’ pass rush. Yeah, that looked like a classic defensive performance from the Saleh or DeMeco Ryans 49ers DC eras. (Other than the weather, it really reminded me of the playoff game in the Lambeau Field snow in January 2022, when Rodgers led the Packers right through the 49ers D on an opening TD drive, but after that … nothing.) And not as much like a Steve Wilks-era game.

So yeah, you could say Nick Sorensen’s DC debut was successful. Shanahan and the defensive players have repeatedly said that they felt like they could return to the energy and connectedness of the Saleh and Ryan defenses. And it doesn’t get any more connected than Fred Warner flying all over the field, the pass rush getting into the QB’s face and the defensive backs knocking away passes.

• Shanahan and Saleh remain close, but every NFL head coach is a rival to each other. Case in point: Shanahan tried to steal Jets DC Jeff Ulbrich away from the Jets last offseason. Saleh blocked him. And you know that Saleh (and his group of ex-49ers defensive players, including Javon Kinlaw and Solomon Thomas) would’ve loved nothing more than to knock around Shanahan’s offense on Monday.

But that did not happen. Shanahan of course loved the 37 total runs and the 180 rushing yards. But another stat I’m sure he liked from Monday: Starting with the 49ers’ third possession (right after the Jets scored a touchdown to go up 7-3) until the end of the game, through eight consecutive 49ers scoring drives, they had the ball for 68 plays. The Jets had it for just 21.

That is just an astounding indicator of complete control and raw power.

On his podcast Monday, former 49ers cornerback Richard Sherman said he’s sure that Shanahan brought some extra oomph into this matchup, and I absolutely agree.

What could Shanahan have been trying to prove to his pal? How about: Even without McCaffrey, Shanahan still called an offense that ran it right through the Jets’ defense. Then Shanahan and Saleh hugged each other at midfield afterward, just like good frenemies always do.