Yet, he also believes he had a "solid" season in 2009, his first as full-time starter.
"(I) can always play better. I played a very solid year. I didn't make too many mistakes, as far as technique-wise, but it was just missing too many that could have turned into big plays. That was just on missed angles," he said. "This year, (I'm) just coming back and starting work on my missed angles. Every other facet can definitely get better. I'll keep on working to get better."
Johnson had 71 tackles last year on defense and added six on special teams, but there is one stat that critics usually point to first – one interception.
"That's just more of how we play. Our defense is very dependent on the front line and everybody just has to make plays that come to them. It's just more just making the plays, controlling what you can control," he said. "Most of the time, you've just got to play within the scheme. If your job is to get on the landmark, you've got to get on the landmark and do your job No. 1 first and that's it."
It isn't like there has been another safety making a haul in interceptions while Johnson has just one. In fact, Johnson's interception was the only one of the season for the safeties. Veteran Madieu Williams had none.
Johnson said he believes he had an opportunity for a few more, and that's what he'll work to improve on this year.
"I had seven pass breakups. All of them could have been great interceptions, but sometimes it's just how the cookie crumbles. You just have to go back to the drawing board, work on tip drills and just looking the ball in every time," he said. "It's really hard to imitate a game-like interception. You've just got to try your best in the offseason to imitate that. Sometimes it just has to fall your way."
The Vikings had 12 regular-season wins last year, but the interceptions were lacking. Defensive coordinator Leslie Frazier believes Johnson has made progress and is more relaxed this year.
"He seems a little more comfortable with what we are doing on defense than he was even a season ago. He's farther along than he was. You got to believe as he gained more experience, he's going to play with a lot more confidence and make the plays that we expect him to make," Frazier said. "The good thing for him is we have a game coming up on Saturday and that will be a chance for him to showcase how far along he has really come."
Head coach Brad Childress indicated the starting job, which is being battled for between Johnson and Jamarca Sanford, would be won during game action over the next four preseason games.
Johnson admitted to being a bit frustrated that his starting job is in jeopardy, but he's going to keep competing for it.
"It's always frustrating whenever you don't get what you want, but the bigger picture is all you can do is focus on yourself. I come out here every day (and) don't focus on what's going on around me," Johnson said. "I can't control the situation. Do I like it? No. But at the same time I don't have any control over it either. All I can do is come out here and get better as a player, get better as No. 25 and do the best that I can do and God has equipped me to do."
Johnson said he didn't want to get into the "compare game" between himself and Sanford, but Sanford, a 2009 seventh-round draft choice, has shown his aggression attacking the line of scrimmage in the first two weeks of training camp.
"Jamarca is a big guy, he's physical, like a hitter. He loves to play in the box and he does a great job all around," Johnson said. "All of our safeties really do a great job – me, Madieu, (Eric) Frampton and (Husain) Abdullah – I think all of us could easily contribute to the team's success this year."
Johnson said he thinks he can do everything as a versatile safety, including a No. 2 receiver, but Frazier's take makes it seem like the team would like to see a more aggressive approach from him.
"The thing for him will be what happens in the games. Will he pull the trigger when he has to? Will he get his hands on some balls? Will he make the tackles that he has to make?" Frazier said. "That is going to be the big test for him."
Tim Yotter is the publisher of Viking Update. Follow Viking Update on Twitter and discuss this story on our subscriber message board.