SANTA CLARA (CBS/AP) — In less than an hour, the San Francisco 49ers added speed and potential to their defensive backfield and talented size and depth to both sides of their line Saturday in the NFL draft.

But not without taking some risk.

READ MORE: Bay Area Horse Trainer Speaks Out After Kentucky Derby Winner Tests Positive For Banned Substance

The Niners selected talented but troubled LSU cornerback Rashard Robinson with their first pick of the day in the fourth round. He brings outstanding speed and a tall, wiry frame to a secondary looking for help, but he also comes with personal baggage and sat out last season after being suspended by LSU coach Les Miles during his sophomore season of 2014.

Robinson was also arrested last June and charged with the unauthorized entry of his former teammate’s apartment. He never played another down for the Tigers and, at age 20, is an early entry into the draft after just eight career starts in college.

But Robinson said those problems are behind him as he gets a fresh start with the 49ers.

“The (unauthorized entry) case was thrown out, it was a big misunderstanding,” Robinson said. “My record was expunged. I had to learn from my mistakes in the past, just manning up to whatever you did and just being honest, showing people you’re trying to move forward from your past and not trying to go back.”

Because of his potential as a long press corner with 4.4 speed in the 40-yard dash, the 6-foot-1, 177-pound Robinson is considered a possible draft steal because of what he could bring to the edge of a secondary that contributed significantly to San Francisco ranking 27th in the NFL in pass defense last season. The 49ers allowed 4,375 yards through the air and got lackluster results from regular starting cornerbacks Tramaine Brock and Kenneth Acker.

READ MORE: COVID: Health Officials Try to Entice Teens to Get Vaccine With DJ Dance Parties, Gift Cards
Ronald Blair

Defensive lineman Ronald Blair of Appalachian State. (Joe Robbins/Getty Images)

The 49ers later fortified both their offensive and defensive lines with their three picks in the fifth round, taking Appalachian State defender Ronald Blair with the 142nd overall selection and Georgia tackle John Theus at No. 145. San Francisco added another offensive lineman at the end of the fifth round with Mississippi tackle Fahn Cooper at No. 174 overall.

Fahn Cooper

Offensive lineman Fahn Cooper of Ole Miss, (Joe Robbins/Getty Images)

Theus and Cooper are expected to challenge for playing time as rookies on an unsettled San Francisco offensive line that will be switching to a zone blocking scheme under new head coach Chip Kelly. The 49ers also added top guard prospect Joshua Garnett during Thursday’s first round.

John Theus

Offensive lineman John Theus of Georgia. (Joe Robbins/Getty Images)

“We did a lot of zone blocking at Georgia,” said Theus, a four-year starter and first-team All-SEC selection last season. “I feel that’s my strong point for sure. It’s something I’ve done my past four years and something we got better at each year. With how big I am, I’m a good athlete and I can get in open space and run.”

Cooper started all 26 games during his two seasons at Mississippi, where he started seven games at left tackle and six at right tackle as a senior while helping the Rebels lead the SEC in scoring, total offense and passing offense.

Blair was a first-team All-Sun Belt Conference selection last season, when he led the league with 19 tackles for loss, which ranked 12 nationally, and was second in the conference with 7.5 sacks. He joins Oregon product DeForest Buckner, San Francisco’s first-round selection, as one of the new faces on the team’s defensive line.

MORE NEWS: UPDATE: Crews Make Progress On Grass Fire Burning Near Bay Shoreline In San Rafael

© Copyright 2016 The Associated Press. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed