Ryan: Boston’s critical 4th line has ‘leaked oil’ this season, but Bruce Cassidy is holding out hope for rebound

(Photo by Steve Babineau/NHLI via Getty Images)

"It's a tough job, but somebody's gotta do it" might as well be the mantra of the Bruins' fourth line.

As much as some checking forwards and bottom-six grinders relish the role of playing a north-south game and leaving welts against the opposition — such a spot in the Bruins' lineup involves far more than just throwing your weight around.

With Bruce Cassidy and his staff looking to hand both Patrice Bergeron and David Krejci's lines more O-zone starts and favorable ice in order to avoid those taxing shifts spent defending in their own end, the lion's share of those daunting matchups typically tend to fall to the likes of a Sean Kuraly, Chris Wagner and others.

Such has been the trend for years now, especially with Boston trying to preserve a  player with plenty of miles tacked on in Bergeron. As esteemed as Bergeron's two-way play has been for years now, the star center has been handed more and more starts and faceoffs in the offensive zone with each new season — giving him, Brad Marchand and David Pastrnak more time spent in the opponent's side of the ice.

Back in 2013, just 41.61% of Bergeron's faceoffs at 5v5 play came in the offensive zone. The only B's regular with a lower O-zone faceoff percentage was Chris Kelly (34.12%).

In 2014, Bergeron's O-zone faceoff percentage at 5v5 play rose to 46.45%. 

By 2016-17? 54.72%. 

2017-18? 61.22%

This season? 63.30%.

Notice a trend?

But as the Bruins continue to feed their top line more reps in the offensive zone, that has led to the B's fourth line regularly stuck with a heavy dose of challenging shifts, headlined by Kuraly and Wagner as the usual suspects in that bottom-six spot.

Since the 2018 season, the duo of Kuraly and Wagner have logged over 1,200 minutes of 5v5 ice time together — with just 29.51% of their faceoffs set in the offensive zone. Quite the ask, to say the least.

It's far from an ideal situation for those two, but Boston has regularly made the most of it, with the play of an Acciari-Kuraly-Wagner line in the 2019 Stanley Cup Playoffs in particular playing a key role in that run — as that trio not only potted some goals of their own, but also successfully negated opposing top-six units, allowing Bergeron and Krejci to land some punches against weaker matchups as well.

In 2021, two-thirds of that fourth line remain intact on this Bruins roster — but the same unfortunately can't be said about the results.