Kendall Sheffield has realized this since arriving at Alabama last summer.

Learning the Tide's defensive playbook? Getting comfortable with everything Nick Saban asks of Alabama's cornerbacks?

"It's been harder than he thought it would be," Cecil Sheffield, Kendall's father, said.

Athleticism? Not an issue.

Sheffield, a five-star recruit last year, is likely one of the fastest and most athletic players in the country. His time of 13.42 in the 110-meter hurdles ranked fourth-best in the country last year among preps. During Alabama's spring testing, the 6-foot, 190-pound Sheffield posted a team-best 37-inch vertical jump and bench-pressed 405 pounds, more than most of the Tide's running backs and tight ends.

So why isn't the redshirt freshman higher on Alabama's depth chart? Learning the playbook and getting comfortable with everything Saban asks of Alabama's cornerbacks have been challenging.

He is, however, improving in both areas.

Continued growth will be key for Sheffield during the Tide's fall camp, which he is set to enter as one of the leaders in the competition for Alabama's No. 3 cornerback job.

"He's had to get much better with his technique," Cecil Sheffield said. "And the press coverages? We didn't press in high school. Kendall's learning all of that now at Alabama. So that kind of put him behind someone like (fellow class of 2015 five-star cornerback) Minkah Fitzpatrick. Minkah's dad said Minkah already had a lot of experience with that stuff and with the press coverages. Kendall didn't. None. Kendall was just athletic in high school. So you could just say, 'Kendall, go cover that receiver over there.' And he could do it easily in high school. In college, you have receivers running 4.3s and 4.4s. If you miss a beat, you're beat. So it's more about technique in college. He still has a long way to go -- just me personally as a dad -- but he's a lot more comfortable."

There has been some nice feedback.

After struggling during fall camp last year, Sheffield improved during the season, making standout plays while working on the scout team. Matched up one-on-one against starting wide receiver ArDarius Stewart in a pre-Cotton Bowl practice, Sheffield made a diving interception.

Reggie Ragland, one of Alabama's defensive leaders last year, said of Sheffield during the winter, "He's going to be a lockdown corner when it's all said and done."

While Sheffield didn't have a breakout spring and worked mostly with the Tide's backup defenses, Cecil Sheffield said he has heard good things regarding his son's development from Alabama defensive backs coach Derrick Ansley.

"He said Kendall's doing well," Sheffield said. "He said he's picking up the playbook more, that his technique is getting better, that he's more comfortable and that he just needs to keep improving and keep fighting because there's a lot of guys up there, but we knew that going up there."

A player leaving has created even more of an opportunity for Sheffield and others.

The spring ended with Marlon Humphrey and Fitzpatrick as Alabama's two starting cornerbacks and Maurice Smith as the Tide's nickel back. Smith deciding to transfer may force Alabama to slide Fitzpatrick inside to play nickel when it goes into nickel or dime defense. That could open up an opportunity for Anthony Averett, Sheffield or freshman Shyheim Carter to step into the outside cornerback spot opposite Humphrey.

"He's ready to compete," Sheffield's high school coach, James Williams, said. "He's excited. He says he's gotten a lot better and that he's learning the system. They play a very good system there, and sometimes it takes longer to learn it and be comfortable with it. And he's comfortable now and definitely ready to get out there and contribute."