Castonzo has had his hands full early in 2012.
It has been a long time since the Indianapolis Colts fielded a quality offensive line.
Going back as far as 2008, the Colts have consistently run out one of the five worst lines in the NFL every single year.
With Peyton Manning at his apex, Indy not only survived, but thrived despite a group that couldn't run or pass block well.
Now that Manning has moved on and Andrew Luck is in the saddle, the Colts desperately need better play from the men up front in order support their young investment.
General manager Ryan Grigson worked diligently to reconstruct the unit, but through two games, the Colts are still suffering from some ugly line play.
Indianapolis is averaging just 3.3 yards per rush. That's 26th in football. Andrew Luck has been sacked five times in two games and been forced to scramble on several other occasions.
There have been three primary culprits behind the shaky start.
What has caused poor line play by the Colts?
The Colts have gone up against two of the best pass-rushers in NFL history in the first two weeks. Combined, they posted zero sacks but did pick up nine hurries.
Left tackle Anthony Castonzo hasn't been perfect, but he largely held his own. With so much to worry about coming from Luck's blind side, it's no surprise the Colts have given up some pressure.
All things considered, the results could have been a lot worse for the Colts.
It's impossible to judge the moves made by Grigson to rebuild the line, simply because the projected starters for the Colts haven't played a single snap together.
Right tackle Winston Justice left the Bears game with a head injury and didn't play in Week 2.
Left guard Joe Reitz has missed both games with a knee injury.
Center Samson Satale was also dinged with a knee injury against Minnesota.
That's three starters down for the Colts, forcing Trai Essex, Jeff Linkenbach and Seth Olsen into the lineup. Essex wasn't even with the team in camp.
By the end of the Vikings' game, Mike McGlynn had moved to center and Essex was at right guard. That means four of the five linemen were either replaced or playing out of position.
All teams deal with injuries, but losing three-fifths of the starting line just six quarters into the season would be enough to cause any team issues.
There just aren't enough good players playing where the coaches want them to play to open holes in the run game or protect the quarterback.
Confusion is a byproduct of the opponents' scheme and a lack of playing time together.
Offensive line play is about more than just any one player, good or bad. It's about the way a unit works together. It would be natural for there to be an adjustment period for the Colts' revamped unit even if everyone was healthy.
A new center and a new quarterback are always going to have a learning curve when they work together for the first time.
The Colts haven't been helped much by veteran blocking back Mewelde Moore, who has looked lost at times.
All is not lost for the Colts' line. Getting players back will help. Obviously, healthy bodies and better players make a huge difference.
As far as Luck goes, the Colts are already making great strides toward protecting him. Consider his first pass of the game-winning drive against Minnesota.
Luck scanned the field for a moment, but then executed a bootleg to his left before the pocket even had time to collapse. While it's possible this was pure impromptu by Luck, it seems more likely that it was a designed roll-out.
The Colts are taking advantage of Luck's mobility to buy him time the line can't provide. That's great coaching and a sound strategy for the future.
As far as the run game goes, the Colts' best solution is to abandon it.
They should run a few scattered draws to keep the defense honest, but until the starters return, it's clear there won't be major running lanes for the backs. It makes no sense to continue to burn plays running the football when they have little chance of success.
Run/pass balance is not nearly as important as making positive yardage on plays. Letting Luck pass more will keep him out of 3rd-and-long situations where he's vulnerable to big blitzes.
It's far too soon to make any judgements at all about Grigson's efforts in rebuilding the offensive line. Until the Colts actually play their projected starting lineup together and in position, it will be a work in progress.
Fortunately for Indianapolis, the single best skill Luck brings to the table is pocket awareness that is in a category with the best in football.
It has already been put to the test too much in the first two weeks, but that's not likely to change anytime soon.