The book on Lane Johnson coming out of Oklahoma cited not only the offensive lineman’s boundless athleticism and promise but also his overall inexperience and unrefined technique.

Some scouts felt the converted quarterback-tight end-defensive end lacked the sharpened mechanics worthy of being a top-five pick. The Eagles didn’t seem to mind. They drafted him fourth overall and quickly promoted him to first-team right tackle in the spring camps.

At this week’s rookie camp though Johnson is strangely one of the most pro-ready prospects at his position. Only five linemen were invited for the first two days with rehabbing third-year center Jason Kelce (knee) serving as the elder statesmen.

Johnson moved over to left tackle while rookie Nic Purcell an Aussie and former rugby player who started nine games at the junior college level worked at right guard and newcomer Michael Bamiro who played three seasons at Stony Brook lined up at right tackle.

Without enough personnel for real team drills the linemen spent most of the time getting an earful from new offensive line coach Jeff Stoutland.

“It’s just trying to get back into football mode” Johnson said. “You go off for a few weeks you kind of lose sight of some of the rhythm you were in. So it’s just getting out here getting back in football terminology and getting out there on the field and doing some drills.”

The Eagles hope Johnson’s learning curve bends much quicker than the last offensive linemen they plucked in the first round. Danny Watkins the 23rd-overall pick of the 2011 draft will report to camp Thursday fighting to preserve his roster spot in his third season a season in which most first-rounders are ready to break through. Watkins has started just 18 games and played in 23 over his two seasons.

Everyone knows the story behind Watkins’ trouble adjusting to the abrasive coaching of then-offensive line coach Howard Mudd a fractured relationship that buried Watkins’ confidence and stunted his development from the onset.

The key for Johnson Kelce said is that he’s more obsessed with playing confidently than making impressions. Johnson is still “green” Kelce added but that’s to be expected.

“The biggest thing I’ve told him since he’s gotten here is don’t be afraid to be mistakes” Kelce said. “They drafted you here because you’re a big fast strong guy. Don’t ever be pulled back. And that’s the biggest thing you see with rookies. I did it myself. Every rookie does it.

“You’re so new and you don’t know things very well and you’re trying to learn everything mentally and you’re doing too much thinking when in reality you should just go out and play. We’d rather have a guy right now at this point a guy like Lane who’s a rookie -- we’d rather him go full out and blow somebody up. If he’s got the wrong guy we can correct that.”