Unbelievable.

That’s the word that a lot of people will use to describe the loss the Pittsburgh Penguins suffered Saturday afternoon.

When Anthony Mantha scored 5:25 into the third period, he extended Pittsburgh’s lead to four. That should have been the goal to officially put the game out of reach.

But fans watched in complete horror as one by one, the Sharks climbed all the way back and won it in overtime.

Per the postgame broadcast on Sportsnet Pittsburgh, this was the first time the Penguins blew a four-goal lead in the third period since March 10th, 1976, against the Buffalo Sabres. In that game, the Penguins went into the third period holding a 6-2 lead over the Sabres, before Buffalo rattled off five straight goals to win it in regulation. A stunned crowd at the Civic Arena watched on.

Almost 50 years later, a similar collapse took place at PPG Paints Arena. It was completely, utterly, bitterly unacceptable from everyone involved.

John Klingberg scored on the power play to make it 5-2. Ok, that’s fine, no big deal. You can’t kill them all!

But the real trouble came later. With a little under six minutes remaining, William Eklund scored to make it 5-3. This was the goal that made it a game again.

A few minutes later, with momentum on their side and nothing to lose, the Sharks pull their goaltender. And this is what kills me about head coach Dan Muse’s management today.

I’ve liked a lot of what Muse has done so far this season. In general, he has the team playing with a lot more energy, and a lot of areas of their game have improved.

But in no circumstance, when the game is on the line and you’re setting up shop to defend your own end, should Erik Karlsson and Kris Letang be on the ice at the same time.

Both blueliners are on very different trajectories this season. Karlsson has experienced a resurgence in his career under Muse, while the slightly older Letang is going through a rough regression right now.

But, two of the team’s most offensive-minded (and defensively-lacking) defensemen were on the ice to try and seal the game. It’s just bad personnel and game management. And it didn’t work.

San Jose, with the goalie pulled, scored to make it 5-4.

Muse then calls his timeout, which was the correct decision. The Penguins were reeling and needed a minute to settle down. But, the message he delivered to his team during that break didn’t take.

Just about a minute later, even though different defenders were on the ice, the Sharks tied it. Silovs laid sprawled out on the ice, as his defensemen tumbled over him.

Sometimes, though, you just need a save.

You can pick out any one of San Jose’s goals in the third period and argue that the defense in front of Silovs could have done more. But when that many goals end up in the net in such a short amount of time, you need your goaltender to be able to nab one of them.

The collapse doesn’t help given the fall from grace Silovs has experienced earlier this year. After his strong start early in the season, he has lost six in a row, nine out of ten, and has an .882 save percentage since the start of November.

Silovs was a problem. The defense was a problem.

But in a loss like this, most of the eyes have to go towards the head coach.

The Penguins still don’t look like they’ve recovered from that loss against Anaheim, where the Ducks scored with 0.1 seconds left to tie it, before winning it in a shootout. Since then, they played a disinterested game against the Montreal Canadiens, where they lost 4-2. And now, they did whatever this was.

This was the seventh time the Penguins have blown a third period lead this season. For now, the book is out on these guys.

The Penguins are a good team, who have surprised the league with how competitive they have been this year. They can keep their motor running for most of the game, but they have one very clear, fatal flaw. They are a fragile group.

So, if you’re an opposing head coach, and your team is trailing by a goal or more in the third period, the message to your team is pretty simple. All it takes is one. One goal against, and the Penguins start to crumble. They can’t handle the pushback.

Even if the Penguins manage to hold onto their next lead, it doesn’t matter all that much. Most likely, it just means the opposing team didn’t want it as much as San Jose did on Saturday.

I’ll be honest, I don’t know how you fix that. Sure, there are some aforementioned decisions you can make to try and mitigate the issue, like not having a pairing of Karlsson and Letang on the ice, or perhaps relying less and less on Silovs.

But no one thing fixes this. It’s a much deeper issue, one that Muse and his staff need to figure out quickly. He certainly is not the main cause of this problem, it predates him years. But now he’s the guy. It’s his team, and it’s his task to try and get these guys to close out a 60-minute effort.