The Bruins had a chance to put their foot on the throat of the St. Louis Blues on Monday night. After a dominant 7-2 win in Game 3, the opportunity was clear: Win Game 4 on Monday and take a 3-1 series lead back home with a chance to clinch the Stanley Cup on home ice in Boston. 

Not only did the Bruins fail to make good on that opportunity, they were suffocated by the Blues in Game 4 and finished the game with barely a whimper. The Blues looked dominant for a majority of the night and pulled even in the series with a 4-2 win in St. Louis. Instead of a potential elimination game in Boston on Thursday, it's now a best-of-three. 

So, who holds the edge now? 

Hard to say considering how difficult it's been to get a read on this series. The teams have traded wins and, through four games, we've yet to see both sides look good on the same night. The Bruins were dominant in Game 1. The Blues bounced back and grinded down the Bruins for a gutsy overtime road win in  Game 2. Boston throttled St. Louis in Game 3. The Blues were suffocating in Game 4. 

It's been a tour de force of resiliency, which seems fitting considering these two teams were among the most resilient in the league this season.

With that in mind, it's fair to think this series is still the Bruins' to lose. In fact, they're still listed as series favorites (-160) and they've got home ice advantage, with Game 5 and a potential Game 7 to be held at TD Garden. 

But it's hard to argue against the series largely trending in favor of the Blues right now, especially if they can play as smart and as clean as they did in Game 4. Discipline has been a major issue for them -- they gave up six power play goals through the first three games of the series, including four in Game 3 -- but St. Louis has been the better team at even-strength in this series. Have a look at the numbers when manpower is even:

  • Shots: 96-85 STL
  • Shot attempts: 188-148 STL
  • Scoring chances: 80-65 STL
  • Goals: 10-8 STL

A big reason for that discrepancy is how little the Bruins are getting from their top players at five-on-five. The top line of Patrice Bergeron, Brad Marchand and David Pastrnak has combined for zero points outside of the power play. The thought was that they might break out after having a big power play night in Game 3, but the Blues' fourth line -- with Oskar Sundqvist back in the fold after serving a one-game suspension -- did a great job to shut them down in Game 4.

The Bruins' second line of David Krejci, Jake DeBrusk and David Backes has been even worse. They also have zero points and have pretty much looked invisible all series long.

Zero points from the top-six at five-on-five through four games. Not great.

If the Blues can play disciplined, avoid taking unnecessary penalties and just stick to playing between the whistles, they should be in good shape. St. Louis has gotten production from its stars. Vladimir Tarasenko has three goals in the series, all of them coming at five-on-five. Brayden Schenn also has three points (a goal and two assists) at even-strength and Alex Pietrangelo is providing ancillary services from the blue line. 

Further worrisome for the Bruins is how strong Ryan O'Reilly came on for St. Louis in Game 4. The Selke candidate has had a surprisingly rough postseason but he found top form in Game 4, scoring twice (including the game-winner) and looking like the two-way force that has earned him comparisons to Bergeron. O'Reilly could be back to playing like himself while Bergeron is struggling to find top form. That would be extremely bad news for Boston.

On the topic of extremely bad news for Boston: Zdeno Chara's status is up in the air after the captain took a puck to the face in Game 4. The gruesome incident left Chara bloodied and battered and apparently did some significant damage to the 42-year-old. He left the game in the second period and, despite returning to the bench in the third period, didn't play again.

The fear is that Chara may have suffered a broken jaw, leaving his status in doubt for Game 5 and beyond. If there's anyone who could somehow manage to play through such an unfortunate diagnosis, it'd likely be Chara. But if he's not able to play through it, that's a tremendous loss for the Bruins. 

Chara may not be the dominant shutdown force he once was but he's still a massively important piece for this Boston team, both on the ice and on the bench. He's averaging nearly 22 minutes a night for the Bruins during this playoff run and has a 59 percent goal share when on the ice at five-on-five. His looming presence would be missed, especially considering the Bruins are already missing a left-shot defenseman in Matt Grzelcyk (concussion).

The drop-off is steep from Chara to whoever the Bruins would theoretically replace him with. Steven Kampfer could get the call, but if Bruce Cassidy wants to replace Chara's left-shot, the only option is rookie Urho Vaakanainen. The skilled 20-year-old Finnish defenseman was a first-round pick in 2017 but he's only played two games at the NHL level -- both of them coming in October before he suffered a concussion and spent the rest of the year in the AHL. 

Throwing Vaakanainen into the fire in the Stanley Cup Final is far from an ideal scenario for the Bruins, but Cassidy's hand might be forced if Chara's injury is significant and Grzelcyk isn't an option. If so, buckle up....no pressure, kid. 

The trends point in favor of the Blues, but trends haven't exactly delivered or been consistent in this series. There's been a huge unpredictability factor. The only real consistency has been on special teams, where the Bruins have continuously outplayed St. Louis. The Bruins also seemingly still hold an edge in net, where Tuukka Rask has been thoroughly solid as the last line of defense while, on the other end, Jordan Binnington's performance has fluctuated more.

So, yes, there's reason to have one hand over the panic button in Boston right now, but there's also reason to take a step back and just breathe. Conversely, there's reason to feel great about where the Blues are at right now, but there's also reason to feel completely uneasy about that confidence. (Don't forget, these are still the St. Louis Blues.) 

Resilience has been the story, the Bruins have a chance to make sure it stays the story with a rebound performance on home ice on Thursday. If they can get it, they'll push St. Louis to the brink and volley resilience back to St. Louis. But right now a lot of signs point to St. Louis being the favorable team. In a series as unpredictable as this one, somehow that feels like it may not be a good thing.