Come Saturday, his barometer will be wearing a different shade of blue and is located four hours west of Indianapolis.
The offensive tackle from Boston College is expected to see his first career action against the Rams. After two weeks of work against teammates, he was asked to gauge where he is and how he measures himself.
"I'm basically just trying to improve every day," said Castonzo. "I recognize the fact it's my second week in the NFL. My number one goal is to improve every day. I figure if I continue to get better, eventually I'll be at the spot where I can play on Sundays."
In assessing himself, Castonzo finds the best way is to resort to videotape. The videotape does not lie, and he sounds like a discerning and honest viewer.
"I just try to look at my technique when I watch the film," he said. "Once I see myself maintaining it (techniques), that's how I know that I am really starting to get better, where I don't really have those little lapses where I'll lean or do something like that. I still have a ways to go. I definitely do, but I definitely see improvement."
After two weeks of review, he sees his performance bar trending up.
"It is, definitely. I expect of myself at some point to be able to win every rep because that's just how I am," said Castonzo. "It's not where I want it to be. It's second-week rookie level right now. I'm definitely just trying to get better."
Indianapolis is one team which does not permit the hazing of its rookies. The club long has held this stance because of the importance rookie on-field contributions are during the season. The club much prefers training camp to be a positive learning environment. Fellow rookie lineman and second-round draft pick Ben Ijalana kiddingly has claimed facing Pro Bowl defensive ends Robert Mathis and Dwight Freeney in practice is hazing enough. Castonzo chuckled at the analogy, but gave his two cents about having to face Freeney daily.
"I…love it. I mean, I love it," he said. "I love it when Dwight (Freeney) lines up against me, and I know he's about to come with some crazy move, and he's going to have a lot of power and speed behind it. I know you can't be the best without going against the best. That's what I have every day in practice. It's a blessing."
Asked what he anticipates as his professional career starts in St. Louis this weekend, Castonzo tells what he is looking for.
"I'm looking to take the steps I've taken these first two weeks and see it on Saturday, see myself sitting down and doing the technique that I've gained throughout these two weeks in practice," he said. "I want to win every rep, that's just how I am. Whether that will happen or not I don't know, but I'm going to try my best to do it."
He admits to being curious how things will go and to see what he can do. Asked if he were nervous, Castonzo admitted he does get nervous before a game, with the caveat that the emotion is teamed with another one as well.
"I'd say I do (get nervous before a game). Yeah. I hold myself to a high standard. When you do that, you get a little nerves going, but my dad always tells me nervous and excited are the same feeling. I get excited before games."
That he is excited about his career starting is nothing unusual for a player in Castonzo's position. Colts veterans tell rookies, whether they are first-rounders or undrafted, to relax, read their keys, know the club will provide an opportunity and then…..play ball. Castonzo will check off all four of those points as he gets his career going on Saturday.