As Mac Jones prepares to step in for Brock Purdy, here's what changes for the 49ers

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We already knew the 49ers' season-opening win over the Seattle Seahawks was about as big as Week 1 victories can be — and that was before Wednesday's news made it even more significant.

Brock Purdy is "a longshot" to play this week against the New Orleans Saints, 49ers coach Kyle Shanahan said before adding that his starting quarterback might be facing a multi-week injury absence due to a toe issue.

That means Mac Jones, whom the 49ers signed this offseason to upgrade their No. 2 QB position, is likely to start.

In an ideal world, nothing will change from an operational standpoint for the 49ers. Shanahan pursued Jones because he believes that the former New England Patriots starter can operate his scripted offense at a high level.

"Mac knows how to play the position," Shanahan said Wednesday. "He can play well in the pocket, distributes the ball well, sees coverage well, can play fast in there. He's got a lot of good film from the NFL."

The problem for the 49ers: Jones might have to show more than just scripted success, especially if Purdy is out for multiple weeks. The 49ers will be without tight end George Kittle (hamstring), their leading receiving weapon from 2024, for at least four games. And they're already down two of their top receivers in Brandon Aiyuk (knee) and Demarcus Robinson (suspension).

That set up a tough-sledding situation for Purdy against the Seahawks. With downfield separation limited, Purdy relied on his off-schedule ability — while he doesn't run a particularly fast 40-yard dash, he's been measured to have an exceptionally fast 10-yard burst — to escape Seattle's pass rush and deliver the game-winning touchdown strike to Jake Tonges.

Jones, who's joked that he looks like fellow (and fictitious) Alabama alumnus Forrest Gump when he runs, doesn't move as well as Purdy — so the 49ers probably can't count on plays like that from their backup.

But the 49ers do have the ability to make life on their quarterback easier this weekend, and that starts with improving the run game in Week 2. The 49ers managed only 3.3 yards per carry against the Seahawks, inefficiency that set up Seattle's defense — which might be one of the NFL's best — for big pass-rushing success against Purdy. The Seahawks delivered pressure on 59% of snaps, the highest rate Purdy has faced in his career.

Put simply, the 49ers cannot afford a repeat of that number against the Saints. Jones will need better protection. They'll have to execute a much more formulaic game plan against a defense coordinated by Brandon Staley, who was an assistant on the 49ers' staff in 2024. New Orleans showed some pass-rushing juice in its Week 1 loss to the Arizona Cardinals, but the Saints did allow 146 rushing yards on 5.4 yards per carry.

There's certainly an opening there for 49ers running back Christian McCaffrey, who was very effective in the pass game (nine catches) while seeing limited running room (69 yards on 22 carries) against Seattle.

"Whether Brock is playing or not, it comes down to executing at a high level and keeping it that simple," McCaffrey said in the locker room Wednesday. "Not trying to do anything special.

"... Mac shined a bunch of times in camp. He's got a whole bunch of starts under his belt. He's played in the NFL. He's played good football before."

Kittle's absence undoubtedly makes it harder for the 49ers to run. As one of the game's most adaptable players, he helps Shanahan disguise whether the 49ers plan to run or pass at the line of scrimmage — and that keeps defenses on their heels pre-snap.

To pick up the Kittle-less slack, expect the 49ers to continue deploying fullback Kyle Juszczyk in a tight end role. Shanahan positioned him as an in-line tight end on 15 of his 37 snaps Sunday; one of those turned into a long catch on a disguised rail route.

"[The line between fullback and tight end has] always been pretty blurred," Shanahan said of his amorphous offense. "They're almost the same thing. Just a very small difference [in] skill sets. But Juice is one of the smarter players I've been around. He's been here for, this is the ninth year now. So we try to switch it up for him to keep intriguing him. We put him in some different [position] rooms. He goes back and forth more. But you know, we ask all of our tight ends to do what the fullback does, too, in case we lose 'Juice' in a game. So, both of them, there's a lot of carryover.”

Beyond that, expect the 49ers to be more reliant on their receivers than in Week 1 — simply because they should have more capable wideouts at their disposal.

Kendrick Bourne, who spent 2021 to 2024 with the Patriots and returned to the 49ers on a one-year deal this week, was back in the locker room Wednesday.

Bourne is taking a crash course on the changes that Shanahan's offense has undergone since 2020 — the end of his first stint with the 49ers — but seems confident that he'll absorb enough knowledge by Sunday to join Ricky Pearsall and Jauan Jennings in the lineup. (Jennings didn't practice Wednesday due to his shoulder injury, but has a good chance to play Sunday.)

In fact, Jones — Bourne's first QB with the Patriots — has already been helping the receiver pick up the playbook.

"We have to adjust," Bourne said at his locker. "Me knowing Mac obviously helps. We have a connection. We can speak to each a certain way, because we're already connected."

So expect the 49ers to continue featuring more of Juszczyk at a tight end alignment along with a potentially increas in three-receiver sets. The goal is to tie the run and pass games together in harmony, and that's how their available personnel sets up to do it best — with Jones likely orchestrating the show from the QB's chair.

"He's a tough guy who will hang in there and deliver the ball where it needs to go," Shanahan said.

• The 49ers signed second-year tight end Messiah Swinson to their practice squad. The 6-foot-7 Swinson is a prototypical "Y" blocking tight end who's modeled his game after former 49er Levine Toilolo, who is 6-foot-8. Swinson last played for the Green Bay Packers, who run a system that's similar to Shanahan's.

Expect the 49ers to either elevate or promote tight end Brayden Willis from the practice squad this week. Swinson will then have an opportunity to earn a game day role over the coming month, while Kittle is out.

• Shanahan said "there wasn't that much of a decision" when it came to cutting kicker Jake Moody after his missed 27-yard field goal against Seattle. The 49ers signed veteran kicker Eddie Piñeiro to replace Moody shortly thereafter.

"I think Jake's got a chance to have a hell of a future," Shanahan said. "He is that talented. But, when it gets to that spot where it is — we all know how last year ended — we know how everyone was looking at him and obviously when it gets to that point, you can see it affecting him from a mental [standpoint]. Then you don't have much of a choice. You’ve got to move on, and hopefully Eddy will come in here and do the job.”

Piñeiro said on Wednesday that he decided between joining the 49ers and the Atlanta Falcons.

"I want to win games," Piñeiro said. "I want to be part of a good culture. I'm in my eighth year of my career and I want to win."