Vikings coach Mike Zimmer pulled aside Harrison Smith after the safety watched 49ers running back Carlos Hyde score on a 24-yard touchdown pass up the middle of the defense.

Why Hyde was left open wasn’t completely sorted out, at least before Smith could look back at the play, but what was clear is Smith wasn’t happy with how the Vikings starters played — especially at the start of Sunday night’s 32-31 preseason victory over San Francisco. Quarterback Brian Hoyer had a 143.3 quarterback rating at halftime, when nearly every Vikings starter was done for the night.

“Terrible. You know, we kind of turned it on after we got hit in the mouth a few times,” Smith said. “You can’t start like that. You can’t give up 14 points that easy.”

Hoyer completed 12 of 17 passes for 176 yards and two touchdowns against the Vikings starters. Smith said he noticed the 49ers’ approach to strategize specifically against the Vikings defense, something Zimmer had said his team wasn’t planning on doing throughout the week.

The 49ers ran a heavy offense with Hoyer finding success off play-action passes downfield. That’s how Hoyer’s first touchdown went 46 yards to receiver Marquise Goodwin, who beat cornerback Xavier Rhodes and safety Andrew Sendejo down the field on San Francisco’s fifth play.

“You got to give them credit where we didn’t cover enough,” Smith said. “We didn’t make any plays. Just got to play better.”

Later linebackers Anthony Barr and Eric Kendricks both jumped into the same zone, leaving one side of the field open for a 49ers third-down conversion.

Preseason debut

Second-year receiver Laquon Treadwell made his preseason debut Sunday night after a hamstring injury had limited him since July 31. He caught all three targets for 36 yards. The 2016 first-round pick showed solid awareness when he floated away from a defensive back for a 14-yard grab to convert a third down.

“Everything’s good, man,” Treadwell said. “I’m just excited to keep going each and every game.”

Treadwell said he expects to play in Thursday’s preseason finale vs. the Dolphins. Starters, which Treadwell was in three-receiver sets for the Vikings, typically don’t play in the finale, but he said he expects coaches to play him due to missing the first two exhibitions.

Praying for Houston

Defensive end Danielle Hunter played high school football in Katy, Texas, a suburb just west of Houston where Hurricane Harvey has flooded the streets, reportedly killing at least five people this weekend.

“I’ve been talking to them every day,” Hunter said of his family. “They’ve been doing all right. Houston has been flooded, but they’re out of the flood zone. So they’re all right. Hopefully they’re all right.”

Rudolph, Robison sit

Tight end Kyle Rudolph did not practice last week, so the Vikings did not push him to play. Rudolph, defensive end Brian Robison, receiver Moritz Bohringer and cornerback Terrell Sinkfield did not play against the 49ers.

Robison, the 34-year old veteran, is not expected to play a snap in the preseason. He has dealt with a leg injury suffered in practice this month, but he said he expects to be ready for the regular-season opener Sept. 11 vs. New Orleans.

Retired life

For the first time in 11 years, former Vikings linebacker Chad Greenway entered U.S. Bank Stadium in a different door than the normal player’s entrance. Greenway and his family of six, with his wife Jenni and their four girls, took their time chatting with team personnel and reporters in the media entrance before an emergency struck.

“Hold it!” urged Greenway, the retired ironman ranking fourth in Vikings franchise history with 1,334 career tackles, to his young daughter Blakeley.

A crisis averted, Greenway was eventually directed to a bathroom in the press box.