Johnson, 24, will participate in training camp and preseason games, but will not practice or play in the regular season until Sept. 29, the day after the Eagles' game at the 49ers. No one has said how the team plans to handle Johnson's absence. The most obvious solution would be to move Todd Herremans back out to right tackle and sub in veteran Allen Barbre at right guard.
It will be interesting to see how Kelly and offensive line coach Jeff Stoutland handle that matter in training camp. They might want the line that will actually start the season to get some preseason reps, minus Johnson. The suspension also raises the stakes if there are other injuries along the offensive line, which features three starters over age 30. The Birds did not draft an offensive lineman this year.
The Eagles, who kept their starting o-line intact through 16 games last season, were anticipating a leap forward for Johnson in his second year. The suspension might make that difficult.
"We're very disappointed to learn of his suspension. We have spoken to Lane about the details of the suspension. He understood what he did wrong and took full responsibility," the team's statement said. "The key for him, however, is to learn from that mistake and move forward with his preparation for the 2014 season."
Johnson's statement said: "In April while training, I mistakenly and foolishly put a prescribed medication in my body to help with a medical issue. I mistakenly failed to clear it with Eagles trainers and check the NFL list of banned substances. I am extremely sorry for this mistake and I will learn from it and be smarter in the future.
"I would like to sincerely apologize to Mr. Lurie, Howie Roseman, coach Kelly and his staff, my teammates and our amazing Philadelphia Eagles fans. This will be very hard on me to not be battling with my teammates for four games - but I will be ready and better than ever when I return."
Just before organized team activities began this spring, Johnson sat down with the Daily News to talk about his offseason. He was noticeably more muscular than he was as a rookie.
"I wanted to come back more developed," Johnson said then. He said he gained about 10 pounds over his 6-6 frame, and weighed "close to 320."
Johnson joins sub linebacker and special-teamer Jake Knott, also a 2013 rookie, who received a four-game PED suspension earlier in the offseason. Knott blamed a nutritional supplement. Previously, the Eagles hadn't had a drug suspension since 2009.
Under Kelly, the Eagles employ a "sports science coordinator," Shaun Huls, who is not available to reporters.
The Seattle Seahawks, who won Super Bowl XLVIII, lead the NFL with six drug suspensions since 2011, not including one that was reversed on appeal. Among those suspended Seahawks was Barbre, the Eagle most likely to step in for Johnson.
On Twitter: @LesBowen