They've given up more than 122 rushing yards in a game just three times and have held opponents to a puny 3.11 yards per carry in their last seven games.
But Johnson's defense will face its biggest challenge of the season Sunday when the Eagles face Adrian Peterson and the Minnesota Vikings in the first round of the playoffs.
Peterson led the league in rushing this season with 1,760 yards. He had a league-high 20 runs of 20-plus yards and averaged 4.8 yards per carry. Has rushed for 100-plus yards in eight of the Vikings' final 11 regular-season games. The Vikings are 7-1 in those eight games.
"He's as good a back as you'll see," Johnson said. "He's a special guy. We know, from going up against him last year. You think you have the perfect defense (to stop him) and one guy slips and falls down in a gap, and all of a sudden, he's got that great explosion and hits it and turns it into a big play.
"We need to keep those long runs down with him. He's going to get some yards. But you just hope he doesn't break any long runs. Because that's where he really kills teams. When he gets those 60-, 70-yard runs. That's where the challenge will be for us. To keep those runs under 10 yards."
The Eagles did a very good job on Peterson last season. They held him to 70 yards on 20 carries in a 23-16 Eagles win. Thirteen of those 20 runs gained two yards or less. Just two were for more than eight yards.
Last season Johnson had the team's video department put together a tape of Peterson's best runs. He inserted clips from the movie "The Gladiator" between the runs. Then he showed it to his defense the night before the game.
"That guy, that guy is a beast," Eagles strong safety Quintin Mikell said. "He's had another great year. He's the key to their offense. We have to play well against him.
"We've got to get everyone to the football. Against a guy like that who can run past you and break tackles, you've got to get everyone to the football. If you don't do that, you're going to be in for a long day."
Johnson has had some pretty good defenses in the 10 years he's been in Philadelphia. But this one may be his best. They were one of just three teams, along with Pittsburgh and Baltimore, to finish in the top five in the league in total defense, run defense, pass defense, points allowed and third-down efficiency.
In the last seven games, they allowed more than 14 points just twice and held opponents to 249.1 yards per game.
"As well as this defense is playing right now, it would've been a shame (if the Eagles didn't make the playoffs)," Johnson said. "I can't remember feeling this good (about a defense going into the playoffs). The biggest thing I see right now is consistency and not giving up a lot of big plays, a lot of big runs. And coverage has been one of the best we've had really."
BY THE NUMBERS: .643 - That's QB Donovan McNabb's completion percentage over his past five games. He has thrown nine touchdown passes with just one interception during that span.
QUOTE TO NOTE: "He's having fun. It's almost like he's playing a video game and (he's saying), ‘I can put this guy here, this guy there.' Everyone's making plays. Everyone's got speed and power. He's in a very enviable position to be able to do that." - Safety Quintin Mikell on defensive coordinator Jim Johnson.
SERIES HISTORY: 23rd meeting. Regular-season series is tied, 11-11. Eagles have won both playoff meetings, including a 27-14 win in the ‘04 divisional playoffs. Eagles defeated the Vikings in Minneapolis last season, 23-16.