Pro Football Focus continues its 32-team offseason rankings with NFL secondaries being the latest entry in the series. The analytics site ranks the 49ers' unit at No. 11 with much of the potential surrounding the addition of All-Pro cornerback Richard Sherman. He expects to be medically cleared for training camp after recovering from a November Achilles rupture.

Sherman and the rest of his teammates will report to training camp on Wednesday with their first practice scheduled for Thursday.

There is also second-year cornerback Ahkello Witherspoon, who is slated to start across from Sherman – a player whom he admired growing up.

"It's incredible the way it worked," Witherspoon said in May. "All I wanted throughout college was to play across from Sherman ... In terms of playing across from him? I just wanted it so I could understand what he knows and learn the game from how he sees it, to build on the athleticism and what I already bring to the game."

Witherspoon registered 32 combined tackles, two interceptions, seven passes defensed, and a forced fumble in nine starts and 12 game appearances last year.

"With Sherman in the fold, it's the 49ers who now have their own makings of the original Legion of Boom," wrote analyst Michael Renner of Pro Football Focus. "You'd be hard pressed to find a longer starting cornerback duo than Sherman and the 6-foot-3 Witherspoon. The latter was one of the most impressive rookies in the NFL a season ago, allowing only 59.6 percent of his targets to be completed. Sherman, on the other hand, has allowed a catch rate of only 47.7 percent for his entire career. There's some projection with Sherman coming off an Achilles injury, but if he's anywhere close to healthy, they should be scary."

Sherman invited Witherspoon to his first ever Elite Cornerback Academy at Stanford University in late June. During that time, the young cornerback had an opportunity to sit down with some of the best in the game. Outside of on-field workouts, players like Aqib Talib, Darius Slay, Xavier Rhodes, and Sherman broke down film and shared what makes them so great in coverage.

"I was watching these guys on TV in college, on Monday Night Football, in the playoffs, and to be around them is just a blessing. It's surreal," Witherspoon told Robert Klemko of The MMQB. "I think this is the group I belong in, and turning on the tape confirms that."

The Sherman-Witherspoon duo could transform a 49ers pass defense that ranked No. 22 in the league last season. With fourth-year veteran Jaquiski Tartt and second-year player Adrian Colbert at safety, the potential for a much-improved secondary is there.

"Since we arrived last year, Jaquiski has impressed us with his play, his work ethic and the kind of teammate he is," 49ers general manager John Lynch said via a statement in April following the finalization of a two-year extension for Tartt. "We believe he's a natural fit in our defensive system, and his abilities will allow him to flourish."

Below are Renner's projected starters in the 49ers secondary and their 2017 grades from Pro Football Focus.

Cornerback: Richard Sherman, 82.7
Cornerback: Ahkello Witherspoon, 81.1
Safety: Jaquiski Tartt, 85.7
Safety: Adrian Colbert, 77.6
Nickel: K'Waun Williams, 80.2