SANTA CLARA >> Drake Jackson likes who he sees in the mirror these days, and not just because he’s added some necessary muscle following a disappointing rookie season.

Time will tell if Jackson ascends to the heights his skillset would suggest as an NFL edge rusher for the 49ers. He was coasting without even realizing it through Corona’s Centennial High as one of the top talents in the country, and that continued for three years at USC.

If Jackson doesn’t reach that peak, it won’t be because he didn’t apply himself after arriving as a pro. He’s even put Kris Kocurek’s mind at ease, and the 49ers’ defensive line coach is known for being blunt and demanding.

“I don’t worry about when I start the truck in the morning if he’s going to be there,” Kocurek said Thursday following a 49ers’ offseason practice. “He’s proven it over time. It can’t be a one-day deal, a one-week deal. It’s got to be consistency over an extended period of time and he’s done a great job with that so far.”Jackson said he’s put on about 13 pounds and has increased his lifting in the squat to 415 pounds (six reps) and the bench press to 315 (three reps) — not staggering totals for an NFL player but a considerable improvement for a player who wasn’t prepared for the rigors of his profession.

Kocurek said Jackson’s strength gains have been “significant.”

Jackson is friendly and loquacious, and while he never came out and said it during a Tuesday media session, it’s clear his work ethic entering the league was a long way from where it needed to be.

When practice ended each day, Jackson was one of the first to his car.

“I just kind of wanted to get out ... I wasn’t focusing on my body, I would say,” Jackson said.

At a season-ending meeting, Kocurek outlined the need for improvement, asked Jackson when he planned to get to work in 2023, and was pleasantly surprised when the date was far in advance of April 15 — the day players were required to report.

Jackson has been a special project ever since. He claims to be “falling in love” with the idea of simulating the kind of 24/7 football obsession that has made teammate Nick Bosa a star.

“Since the day I got back, (Kocurek) was with me every day in the weight room, telling me, ‘Are going to stack a day, or are we just going to let the day stack on you?’ I like challenges and I think he knows that.”

Kocurek said he’s had only two players in 15 years who were truly ready to be NFL defensive linemen from the moment they arrived — Ndamukong Suh in Detroit in 2010 and Bosa in 2019. Both were named NFL Defensive Rookie of the Year.

Jackson said he weighs between 260 and 265 pounds and believes that’s an optimum weight.

But rather than obsess over what the scale says, Jackson is more focused on the process that will enable him to tap his considerable potential in a way that eluded him as a rookie.

“Honestly, the weight doesn’t even matter anymore,” Jackson said. “It’s on me just getting my body right.”

Jackson, 22, has always looked the part athletically. His get-off and bend suggest an edge rushing talent bordering on elite. During the draft process, video surfaced of Jackson doing backflips as if he were a gymnast while weighing more than 250 pounds.

At Centennial, Jackson was the Southern California Defensive Player of the Year as named by the Southern California News Group, and he helped fulfill a dream of his father by accepting a scholarship to nearby USC.

An immediate contributor, Jackson had 5 1/2 sacks and 11 1/2 tackles for losses as a freshman and was named to the All-Pac-12 second team.

But the ascension to becoming one of college football’s premiere edge rushers never came. Jackson flashed but lacked consistency, compiling 12 1/2 sacks in 27 games before opting to come out after his junior season.

Considered a first-round talent early in his college career, Jackson lasted until the second round when the 49ers selected him at No. 61 overall in hopes of finding a pass rusher to pair with Bosa.

Scouting reports noted Jackson’s skillset while questioning his strength and if he was properly equipped to handle NFL linemen who would outweigh him by 50 pounds or more. He broke out the backflip a couple of times as a rookie, but chances to celebrate were few and far between.

In Jackson’s case, the scouting reports were accurate. Jackson did some good things early but then went into a steady fade. He was inactive for Weeks 16 and 18 as well as all three playoff games, relegated to the sideline for the biggest games of his life.

“He was one of the best players out there, a five-star recruit,” Kocurek. “I seriously doubt he ever got told he wasn’t good enough to be on the field. I’m sure it was a humbling experience for him.”

When the season ended, coach Kyle Shanahan and general manager John Lynch talked publicly of Jackson’s need to get stronger and better prepare his body for the rigors of an NFL season.

New defensive coordinator Steve Wilks looked at the tape and was asked what he saw at his one and only press appearance with the 49ers.

“A lot of inconsistency. I saw a lot of talent, a lot of skillset, but someone that needs to get a little stronger, a little bigger,” Wilks said. “He’s working hard, so I’m looking forward to him taking that sophomore leap.”

Jackson had an interception in the final game he played for the 49ers, against the Raiders on Jan. 1.

But even on that play, he was originally walled off by tackle Jermaine Eluemenor, then shoved backwards by 334-pound journeyman guard Alex Bars. Teammate Kerry Hyder Jr. happened to tip a Jarrett Stidham pass directly to him.

Jackson didn’t play again and finished with eight tackles, six assists and three sacks — none after Oct. 16.

If all goes according to plan, Jackson will make a quantum leap in Year 2 similar to that of Aaron Banks, who played sparingly as a rookie second-round draft pick and became a solid starter in place of the departed Laken Tomlinson at left guard.

“When they sat me, I had to take myself from the game and see whatever else is going on that I need to be doing, like I’m doing now,” Jackson said. “It helped me in a way: Instead of being mad or sad from being taken out of the game, I figured out things that I need to do to help myself, to better myself.”