The ultimate measure of a man is not where he stands in moments of comfort and convenience, but where he stands at times of challenge and controversy.

— Martin Luther King Jr.

In November of 2012, Brent Celek was mired in the worst slump of his career. The Eagles tight end was dropping passes. He was making uncharacteristic errors. In one game, he had a throw glance off his hand to a defender (future Eagles teammate Patrick Robinson), who ran 99 yards the other way for a touchdown, and he fumbled in the red zone.

The Eagles lost that Monday night to the Saints and it would have been easy for Celek to duck out early from the visitors' locker room at the Superdome. But true to form, he stood at his stall, answered every question, and held himself accountable for the turnovers — even if the intercepted pass was tossed too wide.

"Those are on me," Celek said then. "I can't make those mistakes."

When the Eagles announced Celek's release on Tuesday, and I stopped to think of my nine seasons covering him and what I would remember most, I thought back to that dismal 2012 season when only so many players would talk after losses and only a few would bear responsibility.

Celek, despite his struggles, didn't cower and hide. He understood the anger of Eagles fans because he was just as infuriated – by his performance and by his teammates who didn't play to their capabilities in what would be coach Andy Reid's last season.

"It makes me sick," Celek said. "This is our job. This is what we're supposed to do, and we're failing at it."

There might not have been another player during Celek's 11 seasons in Philadelphia who took as much pride in putting in a hard day's work. It is why I wasn't surprised when he said last week, in a text message, that he planned to keep playing football.

Some had hoped that Celek would ride off into retirement as a champion. It's likely the Eagles had secretly wanted the same, to avoid having to release their longest-tenured player who, as they said in a statement, "defines what it means to be a Philadelphia Eagle."

Brent Celek gestures to the crowd as he and his teammates travel to the parkway as part of the Eagles’ Super Bowl Parade on Thursday, Feb. 8, 2018.
MICHAEL BRYANT / Staff Photographer
Brent Celek gestures to the crowd as he and his teammates travel to the parkway as part of the Eagles’ Super Bowl Parade on Thursday, Feb. 8, 2018.

But the NFL is ultimately a business, and despite the still-lingering buzz of the franchise's first Super Bowl title, tough decisions must be made. Celek was slated to count $5 million against the 2018 salary cap and, with the Eagles on a tight budget, the sides were unable to come up with an agreement on a restructured deal that would have required a pay cut.

"This one is as tough as they come," the Eagles' statement went on to say, "but in our eyes, Brent will always be an Eagle."

Celek said in a text message that it was a "sad day." He clearly wasn't ready to publicly talk further about his departure. But he made an appearance at the 76ers game and received a standing ovation when he was introduced to the crowd. Celek pounded his chest and said, "I love you."

It will be odd to see Celek in another uniform. There should be a market, but it's unclear how many teams will be vying for the 33-year-old tight end. His receiving numbers have decreased in each of his last five seasons, but partly because he unselfishly took on a lesser role.

The team that ultimately signs Celek will be getting a tireless worker, locker-room leader both by example and verbally, and a versatile tight end who can still catch, block and play on special teams.

But more than anything, they'll be getting reliability. Celek's toughness has become legendary. He played in 183 of a possible 184 games, including the playoffs, over his 11-year career, and if it weren't for a short week, he might have played in a 2012 Thursday night game despite having suffered a concussion the previous Sunday.

Many cringe at the thought of what players put their bodies through and believe that mentality shouldn't be celebrated. But even football's staunchest critics would have to admire Celek's professionalism and his devotion to his craft.

As of November 2015, Celek had played through the following injuries: a torn right labrum (2007), a left high ankle sprain (2007-08), torn thumb ligaments (2008), a deep hip bruise (2010), a torn medial collateral ligament in his right knee (2010), a torn right biceps (2010), a double sports hernia (2011), and a torn posterior cruciate ligament in his right knee (2014).

He made a few appearances on 2016 injury lists with neck and rib ailments, but the extent of the injuries was unknown. Knowing Celek, they were probably significant. He was relatively injury-free in 2017, which could explain why he wants to keep chugging along.

Celek had only one goal growing up in Cincinnati, and that was to play in the NFL. He went at it with steely-eyed determination. In sixth grade, he dislocated an elbow in a game, popped it back in himself and kept playing. In college, he played with a dislocated shoulder.

The injury affected Celek's senior season at Cincinnati and he wasn't invited to the NFL Scouting Combine. But the Eagles still drafted him in the fifth round. He would endure other setbacks, but Celek hardly ever wavered despite the various peaks and valleys.

He was as respected as any player in the locker room, as social-media postings from teammates like Carson Wentz, Zach Ertz, Lane Johnson and Chris Long following his release made clear.

Celek will likely finish his career in another city for another team, like so many other longtime NFL players are often forced to do. But he will return. Celek, who owns businesses and property in Philly, has said that he plans to make the city his home forever.

He will never have to buy a beer in Philly because of the championship high he helped bring to the city, but he will always be beloved because of how he carried himself when the Eagles were at their lowest.