Juan Castillo doesn't stop. Not for a minute. He is vocal. He is energetic. He has his offensive linemen moving every second of a 90-minute spring practice and, even without "live" play or contact against the defense, Castillo learns something new every day about his prospects up front.

So the next two weeks are truly important for Castillo and the O line. The Eagles have practices Tuesday through Friday of this week and then Monday through Thursday of next week and then they break until late July when training camp begins at Lehigh University. Castillo knows the line has question marks -- namely, who is the starting center and can Stacy Andrews rise up and be a standout at the right guard position? -- and he is licking his chops at the prospects of eight practices to gain some more knowledge about his troops.

How good is the offensive line? The Eagles laid out the grand blueprint last year and things fell apart when Shawn Andrews was injured and when Stacy showed he just wasn't able to get his surgically-repaired knee in the proper shape to play at a high level. Even with that, Castillo and the line came together enough well enough as the Eagles won 11 games and scored a franchise-record number of points and was as explosive as any offense in the league until center Jamaal Jackson suffered his devastating knee injury.

Now? You know the names and you know the scenarios. Jason Peters has to be a better, more dominating left tackle, even though he was pretty darn good last season as a Pro Bowl player in his first year as an Eagle. Winston Justice was a revelation after a few tough seasons, and he is now entrenched as the team's right tackle. Todd Herremans is a good, solid left guard who missed the first chunk of 2009 with an injury. Nick Cole is cast as the leading man to replace Jackson, but there are others in the mix, including Mike McGlynn, A.Q. Shipley and Dallas Reynolds. Andrews is in line to start at right guard, but Max Jean-Gilles made sure to lose 30-plus pounds to provide a challenge and become a starter.

Depth is another question entirely, and one that won't sort itself out until the preseason is over. Hey, the entire picture might not be settled until then which, by the way, is the target date for Jackson to return to the field in some way, shape or form.

We all expect the offense to score a boatload of points. The weapons are there, right? Kevin Kolb is the triggerman, and he knows the scheme and he knows the job he has is to make the right reads and get the football out of his hands and into the mitts of DeSean Jackson, Jeremy Maclin, etc.

It all goes smoothly if, and only if, the line plays at the highest level. And that brings us back to these next two weeks.

Castillo is looking for timing, and he is looking for all of his players to use their hands and feet and absorb the technique and handle the mental game as he demands. Having eight practices with five projected starters is golden time for Castillo. It won't be talked about much, not with the abundance of talent -- think Jackson will be a story this week? -- but the play of the offensive line is absolutely huge for the Eagles.

That's the scene setter for the weeks in front of us. The rookies and selected veterans had the spotlight for the previous couple of weeks, and now the full team is here for the voluntary workouts. Having some continuity is really important for the offensive line and they have a chance to achieve some for a couple of weeks.

Castillo will be right there every step of the way, loving it, working his guys, expecting progress from one day to the next.