The Post Sports Live crew offers bold predictions for the Capitals season, which opens Tuesday night in Chicago against the Blackhawks. (Post Sports Live/The Washington Post)

Before overtime began Thursday night at Verizon Center, Washington Capitals assistant coach Calle Johansson, the man entrusted by head coach Adam Oates with the defensemen, leaned in to talk to Connor Carrick. In an NHL career that had lasted, to that point, all of 120 sometimes-uneasy minutes, the 19-year-old had yet to experience what was on tap: four-on-four hockey, next goal wins. So Johansson quickly reviewed Carrick’s responsibilities in the Capitals’ zone, one-on-one.

“That was the second time I saw it,” Carrick said afterward. If “I mess that up, you got 17,000 or so going home unhappy.”

Given the goals they have stated publicly — maybe not “Stanley Cup or bust,” Davey Johnson-style, but not far from it — the Capitals can’t afford to mess up and send these sellout crowds home unhappy. After sleep-walking through the first period of Thursday’s home opener, they overcame a three-goal deficit and beat Calgary, 5-4 in a shootout. Those 17,000 fans? They headed to the Greene Turtle and spilled out onto Seventh St., smiles all around.

But those moments before overtime showed clearly the opposite pulls already apparent on the Caps’ roster: Can a team simultaneously develop players and win?

These decisions keep General Manager George McPhee bleary-eyed. Carrick is an undersized, offensive-minded defenseman who was just a fifth-round pick. No one would have questioned sending him back to junior hockey or, after an impressive training camp that led to him signing an entry-level pro contract, to Hershey of the American Hockey League. That’s where teenagers develop.

And when Carrick, by his own admission, struggled in his NHL debut Tuesday night in Chicago, the decision-making and roster-building became easier to question. Nineteen-year-olds make mistakes. Given this team’s aspirations, how many 19-year-old mistakes can it tolerate?

“He took a lot of heat for the other night, and I think a little bit of it unfair, because some of the goals he was on for, he wasn’t the primary candidate for the mistake,” Oates said. “I think it was because of his age, he took a lot of heat.”

But it’s also because of the Capitals’ position in the league, because raising another Southeast Division banner prior to the Calgary game wasn’t wholly satisfying for a fan base that has paid good money to watch this team develop over the better part of a decade. When that process started, 19-year-olds and the promise of the future was an enticing selling point. Mistakes were expected. Now?

“This team, their purpose is to win,” Carrick said. “Their eyes are on the Stanley Cup year after year. Just making the playoffs doesn’t cut it. That disappoints these guys.

“My goals are whatever their goals are. As an individual, your worth to the team is how good a position you put them in to reach their goals. I’m going to just try and sell myself for what I am, and if it fits, it fits.”

Thursday night, it fit. Early in the second period, with the Capitals down 3-0, Carrick took a bogus hooking penalty and went to the box. But he was heady enough to know that when the Caps killed the penalty, the puck was on Marcus Johansson’s stick in the Washington zone. Instead of heading back to play defense or skating across to the bench to get another forward on the ice, he headed straight to the Calgary blue line, where Johansson’s pretty pass set up the breakaway that led to Carrick’s first NHL goal. The Capitals, sagging and dead-legged, came alive.

“I’m glad he scored, because [Mike Green and John Carlson] are going to get the majority of the minutes, so he’s not going to get as many opportunities offensively,” Oates said. “You know, your first goal, it weighs on you. And I’m sure that just relaxes him so much. He made some great plays, some great reads tonight.”

Had Tuesday’s mistakes, overblown or not, been made with the Plymouth Whalers or the Hershey Bears, no big deal. Live and learn. But here, where 17,000 people expect both to be entertained and go home happy 41 times a year — before the second season starts — yeah, that’s a big deal.

As the Caps’ roster took shape, you could see McPhee mulling this whole conundrum. He talked about it regarding forward Tom Wilson, too. The question is two-pronged: What’s best for the player, and what’s best for the team? Is playing limited minutes in the my-god-this-game-is-fast NHL, and risking mistakes that could cost a point or two in the standings, more beneficial than playing regular shifts — plus the power play and penalty kill — in juniors, where Wilson could be sent, or the AHL, which is an option for Carrick? There may not be a right answer.

Carrick said he could handle what, for a more-established player, would be termed a “demotion” should it come in a day or a week or a month.

“What’s the other option? Quit?” he said. “I’m 19 playing in the NHL. I’m not surprised, but I’m definitely grateful.”

Carrick said this through what remained of a shaving cream pie that had been dumped on his head, a baptism provided by none other than Alex Ovechkin at the start of his postgame interview session.

“I think a lot of kids would like to have shaving cream by Alex Ovechkin,” Carrick said, smiling.

All part of the development process, on a team that would like to consider itself fully developed.