The underappreciated season of Anthony Castonzo

1. He's only been in pain for, oh, the last 19 years. Ask Anthony Castonzo the last time his body felt good – like, really good – and he has to stop and think for a moment. Then he goes back to 1998. He was in the fifth grade. Before the growth spurt. Before football really got started.

He’s long past complaining – what’s the point? It’s part of the thankless-yet-well-paying occupation he’s chosen. He’s the rarely-celebrated, often-gimpy, relentlessly-vilified Indianapolis Colts’ left tackle. He hurts, he plays, he hurts, he plays, he hurts, he plays.

“The difference between being hurt and having an injury is so minute,” Castonzo explains. “When I have an injury, do I really feel that much differently than usual? No. Not really.”

Here’s a stat Castonzo never seems to get credit for: He’s missed three starts since his rookie year. There have been 44 different starters along the offensive line since 2012; Castonzo has been there 54 more times than anyone else. For five years, he’s been about all they can count on. His 100th career start arrives Sunday against Tennessee.

He was about to miss one a few weeks back in Houston. His knee was bad. He sat out practice Wednesday, sat out Thursday, got about a dozen snaps in Friday. Worked out on the field Sunday morning. Wanted to play. Did play. Stared down game-wrecker Jadeveon Clowney for 60-some snaps. Didn’t miss one. Didn’t allow a single pressure. Shook his head in the locker room afterwards.

It was obvious: He’s surprised even himself.

“Probably one of the best games he’s played all year,” coach Chuck Pagano said.

2. Castonzo loves football because there’s a winner and a loser on every snap of every game. “A microcosm of life,” he calls it. His wins are quiet-but-satisfying triumphs, born of preparation and perseverance. His losses are loud and obvious and costly defeats.

“It’s extremely stressful,” he says of playing left tackle. “But it makes you feel alive.”

There is justifiable criticism that comes with being the highest-paid lineman on the team and screwing up as often as Castonzo has the past few seasons. He knows this. He’s no Joe Thomas, no Tyron Smith, no Donald Penn. He’s no Pro Bowler. And maybe that’s what a $42 million contract should’ve gotten the Indianapolis Colts: a Pro Bowl left tackle. No doubt, there is a sector of fans anxious to move on from the team’s longest-tenured position player.

There are even fewer who realize he’s quietly having the best year of his career.

3. Castonzo's unit allowed 10 sacks in a Week 8 home loss to Jacksonville, the most the Colts have allowed in a single game since arriving in town on those Mayflower trucks in 1984. During the Peyton Manning heyday, the unit led by Tarik Glenn, Jeff Saturday and Ryan Diem regularly yielded between 12 and 15 all season. It’s no coincidence, then, that Manning missed one snap in his first 13 years.

That Jacksonville game looked and felt like and was a low point for a franchise that’s slid further and further into NFL irrelevance since coming one game shy of Super Bowl XLIX in January of 2015. The leading culprit was the offensive line. The leading culprit in this town, always, is the offensive line.

“The o-line just has to play better,” star receiver T.Y. Hilton vented after the 27-0 blanking. “Far as receiving, nothing can change. We’ve got to take some pride up front and block for (the quarterback). What if we put them back there and take those hits? We’ve got to start up front. Once we get the o-line going and back in rhythm, we’ll be fine.”

Perhaps the forum for Hilton’s frustrations was wrong; his assessment certainly wasn’t. Ten sacks? Even for a young quarterback like Jacoby Brissett, one with a propensity to hold onto the football too long, this was a flashpoint for Castonzo and his crew. They’d been called to the carpet. And there wasn’t a whole lot they could say to rebuff Hilton’s remarks.

Again: 10 sacks.

It was Castonzo, the seven-year veteran, who faced the cameras a day later, forced to answer the media’s awkward questions about a teammate publicly trashing his unit.

“We’re offensive linemen,” he began. “We’re used everything coming down on us all the time.”

4. The analytics contend that Castonzo’s a top-10 tackle this season, that he’s having the best year of his career. Pro Football Focus has charted every snap of his career. There’s nearly 7,000 of them. Per the site, he’s the second-best run-blocking tackle in the NFL this season, the 19th-best in pass protection. That’s good enough for seventh overall. He’s never finished higher than ninth.

That was his career year, 2014, a season in which Castonzo saw more than 1,000 snaps and allowed all of two sacks. The Colts advanced to the AFC Championship Game. Their decision to lock up their left tackle a few months later with a four-year, $43 million extension was a no-brainer.

“Left tackles like Anthony Castonzo are hard to come by,” former General Manager Ryan Grigson said then. “He’s a team-first guy who works as hard at his craft as anyone I have ever been around, regardless of position.”

But Castonzo stumbled in 2015. And again in 2016. And again at the start of 2017.

It’s one thing to be an undrafted rookie and play poorly; it’s another to do it as a first-round pick with a fat extension.

“I’ve been (expletive) terrible this season,” Castonzo fumed after a disastrous outing against the Saints in 2015. “I’m just going to call it like it is.”

“I have to play better, straight up,” he continued. “Forget what my contract is. As the starting left tackle on this team, my teammates rely on me. I don’t care if I was making $5 a game, it doesn’t matter. They expect me to get the job done and I’m not doing that.”

That rocky start this fall has dissolved into quiet dependability. After allowing three sacks and one hit in his first two games this year, Castonzo’s allowed three sacks and two hits over his last eight – and that includes playing hurt in Houston. He’s on pace to allow 19 hurries on the season, the lowest of his career.

But it hasn’t been perfect. In the fourth quarter of a Week 8 game in Cincinnati, a false start from Castonzo handicapped a critical drive. A series later, he was beaten badly by Bengals rookie edge rusher Carl Lawson. Brissett was bulldozed.

“He’ll flip out on himself,” Colts lineman Denzelle Good says of Castonzo. “You won’t hear it, but you’ll see it. He’ll be gritting his teeth, talking to himself. You can tell how hard he is on himself.”

How does Castonzo weigh his 2017?

“Up and down," he says. "I’ve put together some pretty good strings. I think I’ve been playing pretty well lately.”

A teammate overhears this and pipes in. Offensive linemen are taught humility and selflessness. Unit above the individual. In the Saturday era, Colts blockers were fined (by their offensive line teammates no less) if they were caught talking up themselves to the media.

“Pretty high on yourself there, huh, 74?” injured guard Jack Mewhort shouts from across the locker room.

Castonzo wisely pivots.

“There’s always something you can fix," he says. "I’m constantly looking at my game, and I’m like, ‘What is something someone looking at my game can take advantage of?’”

Asked for those deficiencies, the cracks in his armor, Castonzo shakes his head. Nice try.

“No way I’m gonna give my secrets out and let my opponents know where they can attack me,” he says.

5. He spent his summer in the tech world, taking advantage of an NFL Players Association-sponsored externship. He learned how to code video games in Southern California.

“He’ll talk about advanced software stuff sometimes,” says fellow lineman Joe Haeg. “Some of that is a little complicated for the rest of us.”

“Talking to him sometimes it feels like you’re studying for the SAT,” Good adds.

Castonzo wears so much Jordan Brand that you’d think he was the first left tackle in history to be sponsored by the company. He’s not. But he can dream. “It fits, and it’s good stuff,” says the proud Chicago native. “If they call, I’m listening.”

He eschews reading any form of social media, asking trainers or his girlfriend to block the criticisms that pour in on Twitter after a bad game. He’s matured.

“When I was younger, I’d let all that carry over into my regular life,” he says. “And I’d just be angry all the time. Once a downswing started ...”

No more. He leans on breathing exercises during games to prevent one bad play from becoming five bad plays. Afterward, the tape tells him the story, his coaches, his teammates, nothing more. “Now I’m able to separate football and life, which is essential for me,” he says.

As a left tackle he’s aware of what he signed up for. Play well and he hears little. Play poorly and he hears plenty. For a roster that could be heavily in flux very soon – the Colts will have ample salary cap room this spring, their needs here, there, everywhere – no job seems truly secure.

Castonzo’s been one of the rare bright spots amid a forgettable season, even if nobody is noticing.

“Underappreciated?” Haeg begins before pausing for a moment, then landing on his answer.

“Absolutely.”

Call Star reporter Zak Keefer at (317) 444-6134 and follow him on Twitter: @zkeefer.