A brutal slump for David Pastrnak is coming at worst possible time for sliding Bruins

(Photo by Jim Davis/The Boston Globe via Getty Images)

It would have been easy for Bruce Cassidy to take the Bruins' young D corps to task following Thursday's disheartening 4-1 loss to the Penguins — a result that was even uglier than what one could infer from glancing at the TD Garden scoreboard.

On a night in which the Bruins were booed off their own ice from a crowd of woefully unimpressed fans, Cassidy could have addressed the most glaring gaffes found on a game film that might — for the team's own sanity — be better placed on an ash heap than incorporated into pre-practice video sessions.

For the second night in a row, Boston's D corps struggled, especially youngsters such as Jeremy Lauzon, who — after setting up a pair of Devils goals on Tuesday off of self-inflicted miscues — was promptly roasted by fellow stay-at-home blueliner Mike Matheson on a sequence that looked like something out of an early 70s Bruins game or late 80s Oilers matchups.

But for Cassidy, those gaffes, while frustrating, are some of the lumps that teams must take when younger players are incorporated into the lineup. It may not be pretty, especially in the midst of Boston's extended malaise, but they are to be expected, given the personnel out on the ice right now for a young — and severely banged-up — roster.

What isn't expected, however, are those mistakes and lapses in execution stemming from some of the key cogs in the B's locker room. And yet, such was the case on Thursday night, especially with Boston's traditional offensive conduit in David Pastrnak. 

"I'm not frustrated with those guys, I'm disappointed — that they don't recognize the value of the puck and where we are in the game and they haven't stepped up a little more," Cassidy said of his top players. "I get frustrated with the younger guys that make the same mistakes or can't get their shots through from the point. ... That's just a learning curve for some of them. And some of them will learn it and be better off for it.

"Every young guy that comes in this league has to figure it out, find a way — we're here to help them and eventually you make a decision with them. There's no frustration with the older guys. They know what's at stake. They've been to Stanley Cup Finals so they know the way the games played. They just need to respect it and play that way. My job is to get that message through and get them to understand. Their job is to understand that they are leaders this Hockey Club, and they should know better."

Cassidy didn't name names when it came to calling out his top players, but it was pretty clear when he said "value of the puck" was lost for Boston's big guns. Trailing, 2-1, past the midway point of the third period after Brad Marchand gave his team new life with a quick shot past Casey DeSmith, Boston smelled blood in the water.

But less than two minutes after Marchand's tally, an attempted breakout led to disaster. After receiving the puck from Patrice Bergeron, Pastrnak crossed over the B's blue line and into neutral ice, only to promptly relinquish the biscuit off of a careless turnover. Before both Pastrnak or the Bruins knew what hit them, Boston found itself on the wrong side of a 2-on-1 counter rush, with Jason Zucker firing one home against Dan Vladar to make it a 3-1 game and snuff out any chances of a late-game Boston rally.

It was a fumble that sealed Boston's fate against a red-hot Penguins club, but Thursday's back-breaking giveaway has been just one of many concerning trends with Pastrnak's game over the last couple of weeks.