Castonzo will have Manning's blind side

Bill Polian’s spent a first-round pick on an offensive lineman for the first time in his 14 drafts running the Colts.

Anthony Castonzo out of Boston College should offer an immediate upgrade in Indianapolis. He’s likely to step in at left tackle and replace Charlie Johnson, protecting Peyton Manning's blind side while hopefully also offering a boost to the run game.

Smart and dependable are words attached to him in virtually every review. Smart is a prerequisite for a Colts offensive linemen and dependable is a necessity with Manning’s health at issue if a Mario Williams gets a free shot at him.

Johnson did admirable work the last few years. But he was part of a patchwork operation that has yet to fully recover from the retirement of Tarik Glenn before the 2006 Super Bowl-winning season. Polian traded up for Tony Ugoh, drafting the Arkansas tackle in the second round in 2007 but cutting him after three middling years when he couldn’t win and hold a lineup spot.

Johnson may be a free agent, but he’s a player the Colts probably like as a guard or a versatile sub if they can retain him.

Ryan Diem, the right tackle, slipped last season and will likely have to fight to keep his spot. Jeff Linkenbach could be the big challenger there, or Castonzo could start out on the right.

Another second-year man, Jacques McClendon, might fight his way into a guard job as the Colts revamp the unit.

And Indianapolis could still draft another lineman in the next two days.