Put 53 men together in close quarters, and it's easy to see how differently they cope with disappointment.
After the Cardinals were shellacked by the previously-winless Bills in Week 3, some players milled about the visitors' locker room in Buffalo, animatedly rehashing mistakes. Others stood and dressed quietly, while the optimists reasoned it was a blip in a long season.
Deone Bucannon was despondent.
The Cardinals' third-year money linebacker slumped forward on a stool in front of his locker, in full uniform 30 minutes after the game ended, and burned a hole in the floor with his eyes. He mumbled curt answers to those who approached, furious with what played out on the field earlier in the day.
"It's just what it was," Bucannon would say later. "Individually, as a team, it wasn't up to expectations."
Some Cardinals treat the game like a job. To others, it's much more.
When Bucannon doesn't play well, it leaves him steaming. The standard he long ago set was extremely high, and if it's not met, Bucannon is hard on himself.
"A lot harder than anybody else," linebacker Kevin Minter said.
Professional football players begin, naturally, as star athletes in childhood, where jocks are always held in special reverence. They land atop the social pecking order, which breeds a natural charisma.
Bucannon was indeed a great athlete growing up, but not the life of the party.
The son of military parents, he moved a lot as a kid, from Oakland to Hawaii to San Diego to Sacramento and back to San Diego. While Bucannon holds his parents' careers in high regard -- he was nominated for the "Salute to Service Award presented by USAA" this week for his support of the armed forces – the constant change in locales made him shy and made it tough to assimilate.
Luckily, he could let his play speak for him.
"Growing up, this is what I had," Bucannon said. "This is how I made friends. It was football. When I talked to people at lunchtime, it was from football. I take it very seriously."
The dedication to the sport has served him well, turning a lightly-recruited high schooler into an all-conference performer at Washington State and then a first-round NFL draft pick. His weight room sessions are the stuff of lore. Bucannon came to training camp so jacked that safety Tony Jefferson surmised he was bench-pressing houses during the offseason.
Images of Cardinals money linebacker Deone Bucannon
"I know what it is," said Bucannon, who has "football" tattooed on his left arm. "I'm not blind. I've always been kind of the underdog. I like that, though. I want to go out there and show people that I can do something. If people doubted me, to prove them wrong. I take pride in that."
Here's the conundrum: The very thing that lifted Bucannon to great heights has a downside.
He leads the Cardinals with 66 tackles this season, but no one plays a perfect game. And when Bucannon makes a mistake, it eats at him.
"I get mad over it," Bucannon said. "Everybody has something to work on. That's mine."
The issue rears its head on the snap following his error. Bucannon, steam shooting from his ears, wants to knock a ball-carrier into oblivion.
"Buc kind of gets in that mode," Minter said. "He gets vicious. So you kind of want him in that. Like, 'Hell, yeah, you should be mad.' You know somebody's going to pay for the mistake he made before."
However, if Bucannon overpursues and voids a running lane, or if the call is play-action, he can be out of place. Football is a game of big hits and trash talk, but it's also quite technical.
"Being a middle 'backer, you kind of have to have a calm head," Minter said. "You've got to sit back, take a breath and get to the next play. With us, short-term memory is monumental. If not, they'll bust one or you'll mess up in coverage on the next play."
General Manager Steve Keim puts a premium on players who love football, and it played a significant role in his decision to select Bucannon in the first round of the 2014 draft when the projections posited him a second-round talent. Some players may take their physical ability for granted, but Bucannon couldn't fathom doing so.
"Everybody is blessed with a gift from God," Bucannon said. "Everybody has something that they're better than the average person at doing. I feel like it's our mission to use that, whatever gift that was given to you."
The Cardinals would love a team full of Deone Bucannons, a player so dedicated to his craft he is often the last to leave the building during the workweek.
"You never have to worry about (apathy) with him," coach Bruce Arians said.
It's the "over-caring," as Arians calls it, which can blunt the desired result on the field. Bucannon has heeded the message, making strides of late to control the fury.
"I think all players, as soon as you start to press, you lose something – whether it's technique, whether it's eyes (reading the flow of the play), awareness, whatever it might be," defensive coordinator James Bettcher said. "As soon as you start to press in this game, it happens. I think he's done a really good job over the course of the past few weeks letting go and just playing. He's playing at a very high level right now."
When Minter describes his fiery teammate channeling 'Buc Mode,' it conjures up the image of a predator stalking his unassuming prey. Bucannon is a menace when he zeroes in on his target, closing the gap quickly and laying the wood.
Bucannon just has to make sure when he sees red on Sunday, it's part of a 49ers jersey, not his own rage.
"I want to put my best foot forward on every play, so when there's a play where it doesn't seem like that's happening, of course it's going to take a toll on me," Bucannon said. "I need to get a better way to get past it, instead of just getting angry and shutting everything off. I need to understand that my teammates have my back."
"I know how to channel it," Bucannon added. "It's about not letting it blind me."