ST. LOUIS -- Scottrade Center exploded with sound, with excitement, with the sense of a Game 2 win and a two-game lead and the possibilities to come. The St. Louis Blues were celebrating. The Chicago Blackhawks were frantically trying to indicate that they wanted a coach's challenge.

Referee Dan O'Rourke skated to the red line. He announced, to the assembled crowd, "Chicago is challenging that the play was offside."

It wouldn't be the last time he made such an announcement. In a game-deciding 3:27 of ice time, there were two coach's challenges, one by the Blackhawks, asking to overturn an apparent goal by Vladimir Tarasenko at 12:14 of the third period, and one by the Blues, asking to do the same to a goal by Andrew Shaw at 15:41.

The Tarasenko goal was overturned. The Shaw goal was not.

Those decisions made the ultimate difference in the game, which the Blackhawks won 3-2 to even their Western Conference First Round series at 1-1. But, really, it was a decision made long before that sealed the fate of the Blues.

Video: Situation Room: Goal stands after review

Because, as NHL senior director of hockey operations Kay Whitmore said, had the NHL not instituted blue-line cameras for the Stanley Cup Playoffs, it is likely that the replays would have been inconclusive. The goal, in that case, would have remained a good goal.

"The blue-line cameras situated right on the blue line gives you a true sight line of what's actually happening," Whitmore said, of determining whether Jori Lehtera's skate entered the offensive zone before the puck. "Without those cameras, this would have been a tough call to make. You could probably say that the skate might have been in, but if there's any doubt on the ice, then the original call has to stand."

And this one? This one was close.

"To be honest, this was one of the closest ones we've had," Whitmore said. "You're looking at a puck -- not just when it enters the zone. You're actually looking at when the skate comes off the ice and if it stays on the ice when the puck enters the zone.

"So there was two different things. It wasn't just -- we always have ones where the skate's in the air, and that's difficult enough - but this was one, where's the puck? And the puck is coming just at the split second, so the two things were going hand in hand, and you try to look at reverse angles -- some were a little bit clearer than others -- and you try to make sure that you can determine that the skate was in the air, and the linesmen both determined that that was the right call."

Video: Hitchcock after a 3-2 loss in Game 2

But even as close as it was, Whitmore said, the call is black-and-white. Lehtera was offside. The goal shouldn't count.

"I think the initial purpose of an offside challenge was to rid the game of egregious calls where a player is a foot or two offside, but you can't just do those ones," Whitmore said. "If it's offside, it's offside, and this one was millimeters offside.

"You just have to have as much technology as possible once you institute a rule like this. I think, like I said, there will be a debate probably for a long time [from] hockey purists about whether the intent of this rule was to take down goals like this, but maybe that's a discussion for another day.

"Did that skate in the air, does it have a real effect on what happened after that? You can argue that all day, but the rule is, it's always been, you have to have your skate on the ice crossing the blue line. Until there's a rule change, this is the way it's going to have to be."

But the controversy didn't end there. At 15:41 of the period, with the game tied at 1-1, Shaw scored, tucking the puck inside the right post. The goal first was upheld by Toronto. And then the Blues challenged the play, alleging goaltender interference because Shaw made contact with goalie Brian Elliott's pads with his stick. Elliott reacted immediately, looking around for the officials.

Video: CHI@STL: Blues fans sing to 'Let it Be' during review

The viewing began, by referees O'Rourke and Chris Lee.

They watched it from start to finish in real speed, then slowed down. They watched the overhead shot.

Then, once more.

"What I felt I'd seen originally was pretty much confirmed on the overhead, that Shaw, he gets it with his hand, then reaches out after it goes off the side, makes a play on the puck," O'Rourke said. "The contact is after the puck goes in, and it's also with the help of [Blues defenseman Kevin] Shattenkirk pushing him.

"That's how I felt I saw it on the ice, then also what was confirmed by the overall play at full speed, and then also the overhead really helped."

They felt that Elliott could do his job, that the contact came after the puck had crossed the goal line.

The goal would count.

It took 4:25 from O'Rourke's announcement of the challenge to the announcement that the Tarasenko goal had been overturned. It took 4:26 from the Shaw goal until it was confirmed, a fact that Whitmore acknowledged wasn't exactly optimal.

"I think that's always going to be the argument," Whitmore said. "I think we're always cognizant of interrupting the flow of a game and the tempo and who has the momentum, but I think it's such an important part of the year and it's such an important part of the game, and the second game of a series, that you have to just worry about getting it right. That's the ultimate thing."

They don't want to hurry, to make a haphazard decision, Whitmore said. They needed the time, even if the crowd at Scottrade Center -- or any other arena -- is calling for their preferred decision, right now. Whitmore said he felt good about the calls. O'Rourke echoed him.

"As an official, I don't care how I get to the right call, I just would like to have the right call," O'Rourke said. "The worst thing that can happen for us is leaving the rink knowing that we [messed] something up and cost somebody a game. We want to come in and try to leave no fingerprints. Come in, get the obvious stuff, and let the players play, let them decide.

"Some nights they make it easier for us than others."