''It all goes back to what he's done this offseason,'' Rams coach Jeff Fisher said. ''He was there every day, he's worked, he's taken care of his body and he's determined. If you get in that third and fourth year and play like he has, you should start making those plays when you have that kind of ability.''
A third-round pick in 2012, Johnson looked poised for a breakthrough season a year ago before he suffered a knee injury in a preseason game against the Browns that sidelined him for two months. He returned to play in the final nine games, but admittedly wasn't 100 percent.
Johnson took a different approach to this offseason. Rather than head back home to California, as he had done in the past, he spent most of his time training in St. Louis.
''I went home here and there for the weekends to see my family, but I stayed here and trained with my guys,'' Johnson said. ''My trainers, my speed coach, my weightlifting coach, everything was here. So I stayed here for the most part.''
The offseason work appears to have paid off for the 25-year-old defender, lauded by Fisher him early in training camp for being in the best condition since he had been with the Rams.
''I felt like this is a big year for me,'' Johnson said. ''I just wanted to stay and stay focused.''
He will be an unrestricted free agent next offseason and is expected to be a full-time starter after starting less than half of his games during his first three seasons.
The plan was for the Rams to have a competition between Johnson and second-year corner E.J. Gaines for a starting spot. But Gaines, who ended up starting 15 games a year ago after Johnson got hurt, suffered a foot injury early in training camp and will miss the entire season.
Johnson is the biggest of those three corners, at 6-foot-2 and 208 pounds, and has led the team in interceptions in each of the last two seasons, picking off three passes in 2013 and three more in 2014.
The Rams' defensive line is among the best in the NFL with five former first-round picks and Pro Bowl players in end Robert Quinn and tackle Aaron Donald. The linebacking corps is led by Alec Ogletree and James Laurinaitis, the team's leading tacklers the last two years.
The secondary hasn't had the same kind of success, but Johnson doesn't feel like there is pressure on that unit going into the season.
''We come out here and try to stay consistent and stack good practices on good practices,'' he said. ''I feel like the sky's the limit for us as a defense.''
Notes: Left guard Rodger Saffold and defensive tackle Michael Brockers did not practice. Fisher said Saffold, who suffered an injury in the preseason opener at Oakland last week, will not play in Sunday's preseason game at Tennessee. ... Sixth-round pick Cody Wichmann, a guard, did some individual work at practice after missing time with a calf injury.