It was a common theme.

Each player in the locker room said it.

The coach reiterated it, ad nauseam, during his nearly 10-minute press conference.

The Flyers lost Game 3 to the Penguins 5-1 because of a lack of discipline.

I’m here to tell you that while giving Pittsburgh’s potent power play seven chances (of which they scored on three times) is certainly a way to lose a game, it wasn’t where the game was lost.

Nope. The game was lost in the locker room between the first and second period – before all the penalties started piling up.

The game was lost after the Flyers played perhaps their best period of the hockey season and had nothing to show for it.

A great game plan by Dave Hakstol blew up in smoke and went out the window pretty quickly in the second period when the Flyers stopped believing in the process.

A 1-0 deficit after 20 minutes – even the most energized 20-minutes of the season – wasn’t the culprit either. It was just one goal. The result of one bad decision – the only one of the first period – and the Flyers picked up where they left off immediately after it, so it wasn’t the deflating element.

No, the downfall for the Flyers was the fact that they couldn’t finish their chances – and they had a bevy of them – in the opening 20 minutes. They were in full throttle mode for 20 minutes and couldn’t crack Matt Murray and the Penguins defense – which blocked a ton of shots, yet again.

So, in the second period, the Flyers started a little more tentatively. And when you’re tentative in the playoffs, it leads to mistakes – in this case, stick infractions, that led to a parade of penalties.

A Claude Giroux slash:

…which shouldn’t be a slash, but hey, they call it in the NHL for some reason and they do all the time, so, it is a penalty.

It led to this goal:

(By the way, Andrew MacDonald was being crucified for this, but his skate was taken out from under him by Patric Hornqvist’s stick, and, well, the snow angel ensued, but really, that’s just a good Penguins power play.)

Then a couple minutes later, Jake Voracek does this:

And of course, the Penguins answer with Evgeni Malkin providing the power play honors:

Oh, and then an NHL Playoff record for the fastest two goals ever scored was tied just seconds after that:

And there was your hockey game.

But why did it come off the rails? Why was everyone talking about how good a first period it was and then it just went south in the second?

Because the Flyers became frustrated with themselves and started doubting what they were doing well because it hadn’t yet yielded fruit.

In the first period the Flyers were really taking it to the Penguins. They were faster. Stronger. More determined.

The opening minutes were insane. The roof of the Wells Fargo center was ready to blow off. Sean Couturier was playing at another level. He was pounding every Penguin he could. He wallpapered Crosby a couple times. He was in the head of Kris Letang, who was more concerned with trying to push Couturier’s helmet over his eyes from behind than actually playing the game.

And all the lines were buzzing. They were creating chance, after chance, after chance.

And just not cashing in.

There was this:

And this:

And this:

And this:

This was all in the first period, mind you.

But the death knell came for the Flyers in the final 1:43 of the period.

Carl Hagelin went off for slashing and the Flyers went on the power play. They had the puck in the Penguins zone the entire 1:43, got two shots, and couldn’t score.

They went into that locker room between periods and started wondering if what they were doing was working.

It was, but self doubt started to creep in.

It’s what created the more tentative approach to the second period, which in turn led to the stick infractions – because they were playing a little slower – and in turn led to three power play goals for the Penguins.

It’s that simple. They had the Penguins on their heels a bit – and they couldn’t knock them over, and then just stopped trying hard enough to do so.

Look, this Penguins team is vulnerable. Their goalie, although he had a solid Game 3, is not as good as he was last season.

The defense, beyond the top pair, is pedestrian. The depth, while good, is a little less than a season ago.

It’s why Penguins coach Mike Sullivan had to front load his lineup and put his six best forwards all on the same lines for Game 3, rather than spread them out, as he is wont to do.

It was an adjustment he felt was needed after Game 2.

Dave Hakstol made no such adjustment – at least not until the game was practically out of reach.

And while I still don’t understand why Travis Konecny isn’t on the top line using his speed, skill and pest-factor to agitate the Penguins further, I won’t knock Hakstol here for sticking with what worked in Game 2.

But the time is nigh for something different. The Flyers power play isn’t working. They switched it up to get two guys net front, rather than two along the half wall, and that didn’t help either.

The line combinations aren’t good enough. Hakstol needs to continue to do what he’s done well in these playoffs so far and attack the Penguins vulnerabilities – and the players have to buy into that gameplan, not just for 20 minutes, but the entire game – hell, the entire remainder of the series.

Oh, and one other thing. The Flyers’ six best players have to play, at least on par, with the Penguins six best players.

If they don’t, they’re going to lose. Plain and simple.

It’s about time Claude Giroux and Jake Voracek really take a bite out of the offense in this series as they’ve been inconsistent.

Ivan Provorov and Shayne Gostisbehere didn’t have a great Game 3. They weren’t bad, but they were much better in Game 2.

Couturier was fine, but Wayne Simmonds continues to be invisible. I’m told his injuries are even worse than we’re to believe. I’m told it’s a shoulder and a hip injury that are affecting him most. It’s had an adverse effect on his skating. He’s not winning board battles. He’s playing on sheer will power, and even that might not be enough.

It’s really a shame, because we all know the kind of player Simmonds really is, and to see him like this is disheartening.

And oh yeah, in case I haven’t said it enough – Free TK.

It’s the only way to win Game 4 – which has become a must-win game now.

Otherwise, we’ll be talking about the off season by the weekend.