One luxury Baltimore has this year is its depth at cornerback.

Lardarius Webb, Cary Williams, Jimmy Smith and Corey Graham are locks for this year's roster, leaving a maximum of two more spots up for grabs. Three corners are vying for those last two positions -- Asa Jackson, Danny Gorrer and Chykie Brown.

Jackson, a rookie from Cal Poly, a Football Championship Subdivision school, is hoping to use his versatility to make the squad. He's impressed at cornerback in practice but has made his biggest mark on special teams. Against Detroit on Friday, Jackson fielded a punt 85 yards away from the end zone. He criss-crossed the field, beginning left and breaking outside to the right, coasting into the end zone.

Jackson began celebrating, not knowing the play was nullified by a holding penalty committed by rookie linebacker Nigel Carr.

"It’s the preseason, and that stuff is going to happen," Jackson said. "That’s why we play the preseason -- so we can correct those mistakes that count against us in the games that count. We’re going to get that stuff cleaned up. That’s not stuff that we usually do, especially on special teams.”

Barring injury, it'll be tough to get onto the field on defense with at least four cornerbacks in front of him, assuming Jackson makes the 53-man roster. So it's special teams where the rookie has a chance to contribute.

Jackson was a return specialist at Cal Poly, where he returned both kicks and punts. He was a standout corner with the Mustangs, with eight interceptions during his four years. He returned three of those picks for touchdowns.

Listed at 5-10, 191 pounds, Jackson doesn't have the ideal size of an NFL cornerback in a league featuring big and long wide receivers. He's looking to prove the skeptics wrong and latch on with the Ravens this preseason.

“I’ve used that as motivation for a lot of things, and I like when people tell me I can’t do something because then it gives me that extra fire and extra passion to go prove them wrong and get whatever the task is done,” he said.

Jackson's made some plays on the defensive side of the ball that's wowed those in attendance.

The mental approach to the game wasn't as intense in college, he said. It's been an adjustment for Jackson to absorb the Ravens' defensive scheme.

"My last three years in college, I knew everything about our playbook, so I didn’t have to study as much or go over my material as much," Jackson said. "I could just watch film on what the other team was doing.”

Jackson was drafted in the fifth round, and the Ravens have a history of holding on to their draft picks selected that year. With the cornerback position deep this year, Jackson's aware he's not going to make the 53-man roster by just being a corner.

He knows he'll have to make more plays like he did in the return game against Detroit to show the coaching staff he's worth keeping this year.

"It’s the way I’m going to make this team," Jackson said. "I was really happy that I was at least able to get that on film, even though it didn’t count. I am definitely someone who can be of value on special teams to this team.”

Follow Ravens reporter Jason Butt on Twitter: @CBSSportsNFLBAL and @JasonButtCBS.