Colts' O-line has concerns -- and upside

You wouldn’t know it by the number of sacks it allowed, but the Colts’ offensive line was a major liability last season. Which is precisely why the team selected Anthony Castonzo with the No. 22 pick in the draft and then quickly addressed the position again by trading up for Ben Ijalana with the No. 49 pick.

These are two fine prospects. And Castonzo may have been the most NFL-ready of this year’s rookie offensive tackle class. But how could the lockout and lack of practice time to this point hinder the development of Indianapolis’ big men?

What we really don’t know is how much Peyton Manning has been coaching up these two -- and the rest of the Colts’ line and offense for that matter -- during the lockout. Obviously, there might not be a better teacher than Manning for instructing a young player on the intricacies of the Colts’ complex offense.

Manning was sacked only 16 times last season. But he is truly a master at diagnosing pass-rushers pre-snap, feeling pressure and getting the ball out of his hands before being sacked. He made below-average pass protection look quite good. However, with poor play from his offensive line, the Colts were not able to throw deep as often or as well as they have in years past.

But the biggest problem last season was the running game. And this too affected Manning in a negative manner. Manning is great at so many aspects of playing quarterback, but what he might do as well as anyone who has ever played the game is getting his offense into situations where it doesn’t run a bad play.

He has a lot of movable pieces at his disposal and is able to maximize what a defense gives him. But if he doesn’t trust his running game and doesn’t feel confident that the ball carrier can do damage to under-manned defensive fronts, Manning then loses the ability to audible to run plays to some degree. And that negates some of Manning’s best skills and methods for dismantling a defense.

The staple of Indianapolis’ running game is its zone stretch play, which needs the offensive line to more or less move in unison and create a moving wall for the running back to choose the best path. Such continuity takes time and getting the new starters up to speed could take a lot of practice.

Last year’s starting left tackle, Charlie Johnson, is up for free agency. And right tackle Ryan Diem is scheduled to make more money in 2011 than his 2010 performance on the field would justify. It is possible that Castonzo is the starting left tackle on opening day and Ijalana starts on the right side.

That sounds a bit extreme, and Ijalana might be best served starting his career off at guard. Johnson would still be a valuable guy to bring back as either a sixth offensive linemen, or more likely, as a starting guard and insurance policy for Castonzo. It also is not a foregone conclusion that Diem will be released.

Jeff Saturday remains very sturdy at the pivot, especially in protection, but other than that, there are a lot of questions with this group as it stands today. But there is also a lot of room for improvement -- which could be frightening considering the firepower Manning is getting back from injuries.

Scouts Inc. watches games, breaks down film and studies football from all angles for ESPN.com. Follow Matt Williamson on Twitter @WilliamsonNFL