Kristal Kerley’s hands were shaking before kickoff Monday at Levi’s Stadium.

Her husband, wide receiver Jeremy Kerley, was about to make his 49ers debut, 15 days after he’d arrived in a trade. It was a prime opportunity to revive a solid career that had gone south.

After 182 catches in five seasons with the Jets, he was released in March. After five months in Detroit, he was dealt to the 49ers for a backup guard, Brandon Thomas, who is on the Lions’ practice squad.

Now, he was suddenly the 49ers’ primary slot receiver and kick returner in the season opener against the Rams. But had he adequately digested the playbook? Would he have rapport with a quarterback he just met? Would this be a bright beginning or the latest dead end?

“When I first sat down, I was nervous and I was shaking a whole lot,” Kristal Kerley said. “It’s one of those things where he’s going to do good and the fans are going to love him. Or, if he makes too many mistakes, they’re going to be mad and I’m going to have my mama-bear, wifey claws out because I can’t have anybody attacking my husband.”

The good news for the Kerleys: Kristal’s claws were kept under wraps.

The home fans loved Kerley, who led the 49ers in targets (11), catches (seven) and receiving yards (61) in a 28-0 win over the Rams. Kerley, who also returned two punts for 11 yards, played 54 of 81 snaps and provided one of the 49ers’ biggest offensive plays: His diving 18-yard catch on 4th-and-6 in the second quarter sustained a touchdown drive that gave the 49ers a 14-0 lead.

“We picked the guy up two weeks ago and he had seven catches,” head coach Chip Kelly said. “If we picked him up last week, he’d probably have 10 if we didn’t screw him up.”

Yes, Kerley, who recently got a permanent nameplate over his locker, looked comfortable even though he wasn’t quite at home. He didn’t move from a hotel to his new apartment in Santa Clara until Wednesday. And he spent part of the weekend before kickoff being quizzed on his new playbook by Kristal, a former All-America sprinter at TCU he met in college.

“I’d throw out (plays) to him,” Kristal said, “and he’d tell me where he’s supposed to move to.”

On Aug. 28, the Kerleys, who have children ages 7, 3 and 2, discovered that Jeremy would be moving to the 49ers.

They heard from his agent, Jeff Nalley, who called around 8 a.m. and began by saying he had good news: Jeremy would be leaving a team that was likely to release him to play for a team that had just lost its lone viable slot receiver, Bruce Ellington, to a season-ending hamstring tear.

In addition, he noted Kelly emphasized Kerley’s position in the 49ers’ no-huddle offense. Jordan Matthews had 152 catches (and 232 targets) as Kelly’s slot receiver in Philadelphia from 2014-15.

Kerley quickly became swayed by his agent’s good-news pitch: “Knowing Chip Kelly was the head coach and I might have a real chance to be the slot receiver in his offense, it kind of clicked: ‘You might be getting the ball. You might want to hop on this.’”

And Kristal provided more reason to feel good about the trade: “My feeling was you’re going from Detroit to Cali. C’mon, you have to smile, right?”

Until Monday, football hadn’t given Kerley much to smile about for over a year.

In 2015, he was phased out of the Jets’ offense after head coach Todd Bowles and offensive coordinator Chan Gailey were hired. Part of the reason was that the new staff preferred bigger-bodied receivers. Kerley, 5-foot-9 and 188 pounds, finished with just 16 catches despite playing in all 16 games.

In March, just 17 months after signing a four-year, $14 million extension, Kerley was released by the Jets and signed with the Lions. However, Detroit signed former 49ers wide receiver Anquan Boldin just before training camp and Kerley began to get the sense he might be departing Detroit sooner than he expected.

“You’ve got a 14-year vet coming into a team and he really only plays the slot,” Kerley said. “So you already kind of know what it is.”

And it was something Kerley had rarely experienced in his athletic career.

At Hutto (Texas) High, he was a four-year starter at quarterback and defensive back. In baseball, he was a pitcher who also played shortstop and center field. Kerley said his fastball hovered around 94 mph and he received a scholarship offer from Stanford. In track, he was second in Class 3A in the long jump and triple jump as a senior, finishing behind Titans wide receiver Kendall Wright in both events.

His success continued at TCU, where his receiving and returning exploits made him one of the three finalists for the Paul Hornung Award, which is given to the nation’s most versatile player. Then, one year after the Jets selected him in the fifth round in 2011, he had career highs in catches (56) and yards (827), a breakout season that led to his contract extension.

Given that background, he didn’t expect to be released and traded in a five-month span.

“It’s been humbling in the sense I’ve never been through anything like that,” Kerley said. “But for someone who doesn’t know how to handle the situation, it could be demoralizing and that didn’t happen.”

The string of rejection came not long after Kerley was stunned by the death of his “little brother,” Josh Wilson, 25, who was in a single-car accident near Hutto in October 2014. Kerley and Wilson were cousins, but they referred to each other as brothers due to their inseparable bond.

Kerley continued to text Wilson after his death, and the painful loss provided a new perspective on his job. The football-obsessed Wilson, who was also a talented athlete, wasn’t jealous of Kerley’s success, instead reveling in it, and was among his biggest fans. Kristal said Josh lived through Jeremy, who was determined to honor his memory.

Now, with the 49ers, it appears he’ll have plenty of chances to do so.

“For the most part, I didn’t really play for something,” Kerley said. “I just played because I was good at it and it was fun. I never really had a big motivation to go out and prove something to anybody other than myself. ... When he passed, I decided I was going to dedicate myself to play for him. He loved the game so much. Every time I step on the field, I know he’s watching. It’s like, “What would he want me to do?’”

Eric Branch is a San Francisco Chronicle staff writer. Email: ebranch@sfchronicle.com Twitter: @Eric_Branch

Davis out for Sunday

Backup right tackle Anthony Davis of the 49ers has been ruled out for Sunday’s game at Carolina because of a concussion suffered in Thursday’s practice.

Davis did not report his concussion until after practice, which is why he was not listed on the injury report until Friday, the team said.

In 2014, Davis suffered his first concussion and was sidelined for four games while he struggled with serious symptoms. Davis said he felt as though he was in a “white fog” for the first few days after his concussion.

He left the NFL in June 2015, citing a desire to let his “brain and body” heal, although he said during training camp that he wasn’t having post-concussion symptoms when he returned to play at the end of the 2014 season.

Last Saturday, Davis missed practice amid a report he was considering retirement, which he denied this week.

Davis and head coach Chip Kelly cited a “miscommunication” as the reason he missed the practice. They also said his sudden move from starting right guard to backup tackle after his practice absence was Kelly’s decision.

With Davis sidelined, John Theus, a rookie fifth-round pick, will serve as the swing tackle Sunday. If left tackle Joe Staley was sidelined, it’s likely right tackle Trent Brown would slide over to his side and Theus would assume Brown’s spot.

—Eric Branch